Expandable introducer sheath for medical device

ABSTRACT

An introducer sheath for the insertion of a medical device into a blood vessel having an expandable sheath. The sheath has a length, a thickness, and proximal and distal ends. The expandable sheath has a frame extending longitudinally between the proximal and the distal ends, and having an exterior surface and an interior surface that forms an interior lumen along the length of the frame. The frame is configured to achieve an expanded state and a contracted state, the expanded state forming an expanded cross-section in the lumen for passing a medical device therethrough. The frame has a smooth coating about the exterior surface and protrusions extending into the lumen along the interior surface. The introducer sheath can be introduced into a patient in the contracted state, with the distal end of the introducer sheath prevented from moving in the proximal direction by an abutment against a dilator end surface.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.16/540,922, filed Aug. 14, 2019, which claims priority to U.S.Provisional Application No. 62/718,681, filed Aug. 14, 2018, thecontents of each of which are hereby incorporated by reference in theirentirety. This application is related to U.S. patent application Ser.No. 16/277,378, filed Feb. 15, 2019, which published on Aug. 15, 2019 asU.S. Patent Application Publication No. 2019/0247627 A1, the content ofwhich is also hereby incorporated by reference in its entirety.

BACKGROUND

Intracardiac heart pump assemblies can be introduced into the hearteither surgically or percutaneously and used to deliver blood from onelocation in the heart or circulatory system to another location in theheart or circulatory system. For example, when deployed in the heart, anintracardiac pump can pump blood from the left ventricle of the heartinto the aorta, or pump blood from the inferior vena cava into thepulmonary artery. Intracardiac pumps can be powered by a motor locatedoutside of the patient's body (and accompanying drive cable) or by anonboard motor located inside the patient's body. Some intracardiac bloodpump systems can operate in parallel with the native heart to supplementcardiac output and partially or fully unload components of the heart.Examples of such systems include the IMPELLA® family of devices(Abiomed, Inc., Danvers Mass.).

In one common approach, an intracardiac blood pump is inserted by acatheterization procedure through the femoral artery using a sheath,such as a peel away introducer sheath. The sheath can alternatively beinserted in other locations such as in the femoral vein or any path fordelivery of a pump for supporting either the left or right side of theheart.

The introducer sheath can be inserted into the femoral artery through anarteriotomy to create an insertion path for the pump assembly. A portionof the pump assembly is then advanced through an inner lumen of theintroducer and into the artery. Once the pump assembly has beeninserted, the introducer sheath is peeled away. A repositioning sheathcan then be advanced over the pump assembly and into the arteriotomy.Replacing the introducer sheath with the repositioning sheath duringinsertion of a medical device can reduce limb ischemia and bleeding atthe insertion site in the skin (and/or at the insertion site within thevessel) because of better fixation of the sheath to the patient whenused with a hemostatic valve.

Since commercially available tear away introducer sheaths are notradially expandable, the inner diameter of the introducer sheath mustalways be large enough to accommodate the largest diameter portion ofthe pump assembly such as the pump head even if other parts of the pumpassembly, such as the catheter, have a significantly smaller diameter.In this example, the introducer creates an opening that has an outerdiameter wider than necessary to allow passage of the pump catheter intothe vessel. Then, the introducer sheath is peeled or torn away andreplaced with a lower-profile repositioning sheath. Removing theintroducer sheath by peeling it away presents several challenges. Forexample, introducers can tear too easily and/or prematurely, leading tobleeding or vascular complications. Some introducers may requireexcessive force to tear away for removal. If a physician applies toomuch force, when the introducer finally tears, the physician mayinadvertently shift the position of the pump within the heart. Thisconfiguration also complicates the design of the hemostatic valvelocated in the hub of the introducer which also needs to tear. Further,a peel away introducer sheath leads to a larger vessel opening after thesystem is removed, which can complicate vessel closure.

Medical introducers for other applications than inserting heart pumpshave expandable sheath bodies which may expand radially to allow passageof percutaneous devices into the patient's vasculature. These existingexpandable introducers are for relatively short-term use and may bedesigned to prevent thrombosis between the sheath body and an indwellingcatheter. These introducers are inserted having inner diameters smallerthan the outer diameter of the device being introduced. The introducersexpand to allow passage of the device through the sheath and into thevasculature and then may shrink again after the device has passed. Inthe current state of the industry, these expandable introducers requirea distinct expandable feature, e.g. a longitudinal fold or crease or alumen for injection of a fluid (e.g. saline) to transition from acompressed state to an expanded state. Because these existing expandableintroducers are intended for relatively short-term use, clot formationon the outside of the introducer sheath may be unlikely. However, ifleft in for longer periods of time (e.g. >1 hour, >2 hours, >6 hours, >1day, >2 days, >1 week), clots may form on the outside surface of theexpandable sheath mesh, and risk being dislodged into the blood streamat a later time. Additionally, some commercially available expandablesheaths are completely flexible and therefore do not provide anyrigidity within their structure thereby leading to kinking or bucklingduring insertion or withdrawal of a percutaneous medical device.

BRIEF SUMMARY

Systems, devices and methods for insertion of a medical device (e.g.,intravascular medical device) are presented. The devices are deliveredthrough an expandable introducer sheath. The expandable introducersheath is configured to remain in an insertion path (e.g., anarteriotomy) for relatively long durations (e.g., >1 hr, >2 hr, >6 hr,or any suitable duration). Use of an introducer sheath capable ofexpansion allows a smaller size sheath to be used for insertion and canallow the vessel opening to spend less time at a larger diameter,notwithstanding the sheath being used for longer durations. For example,the expandable introducer sheath can more easily recoil to a smallerdiameter after insertion of the pump, which allows the opening of thevessel to recoil to a more natural position. Additionally, because themedical device only momentarily passes through the vessel wall, theopening in the vessel is expected to be smaller than if a largernon-expandable sheath is used. Still further, since the medical deviceonly momentarily passes through the vessel, friction between the device,sheath, and vessel wall is minimized and there is a reduced axial loadand reduced stress on the vessel. That is, the sheath is a smaller sizeand is therefore not pushing or pulling the vessel along the axis of theinsertion/removal path. Instead, when the device passes through thevessel, the vessel is expanded outward radially.

An expandable introducer sheath structure comprises at least one frameand one coating. A coating is applied to the surface of the sheath tofacilitate passage inside the patient. In some embodiments, the coatingis applied on the inner surface of the sheath, which is an innerdiameter biased approach. An inner-diameter biased coatingadvantageously provides for a thin coating thickness and, advantageouslya relatively smaller force is required to expand the sheath compared toa force required to expand a sheath having a coating without any bias.In alternative embodiments, the coating is applied on the outer surfaceof the sheath, which is an outer diameter biased approach. Anouter-diameter biased coating advantageously provides a smooth outersurface which reduces the risk of clot formation and minimizes frictionwhen inserting a device through the expandable sheath. For example, theuse of a smooth outer surface advantageously minimizes the risk of clotsforming on the surface of the expandable sheath, and a corrugated innersurface minimizes the surface area of the expandable sheath in contactwith a device being pushed through, thereby minimizing associatedfriction forces. The outer-diameter biased coating furtheradvantageously provides for a thin coating thickness, and advantageouslya relatively smaller force is required to expand the sheath compared toa force required to expand a sheath having a coating without any bias.The outer-diameter biased coating advantageously allows the sheath frameto expand and contract as desired, i.e. the outer-diameter biasedcoating does not immobilize the frame at a fixed diameter because thethin coating thickness is such that the coating does not encapsulate theportions of the frame where frame elements intersect. For example, for abraided frame having braided elements in an over-under braid pattern andan outer-diameter biased coating, the outer diameter biased coatingadvantageously is thin enough that it does not reach encapsulate anoverlap of braided elements, i.e. the outer-diameter coating does notextend to the braided elements located under other braided elements inthe over-under braided pattern.

The expandable sheath is configured for insertion into the vasculatureof a patient with a dilator assembly. For example, the expandable sheathhas a geometry that enables the expandable sheath to be held in astretched configuration for insertion with the dilator assembly, andreleased after insertion into the vasculature of a patient. For example,the dilator assembly comprises an inner dilator and outer dilator, andthe distal end of the expandable sheath is configured to interface withboth dilators such that the distal end of the expandable sheath cannotmove toward a proximal end of the pump assembly. For example, the distalend of the expandable sheath can have a larger thickness than athickness of the remainder of the expandable sheath body.Advantageously, the thicker distal tip of the sheath abuts a distal endof dilator system, which prevents the distal end of the expandablesheath from slipping toward the proximal direction during insertion intothe vasculature.

The expandable introducer sheath structure can be manufactured usingthermal bonding or an outer-diameter biased dipping. Advantageously,thermal bonding or an outer-diameter biased dipping produce the smoothouter surface of the sheath, without losing the desired spring-likeexpandable nature of the sheath.

Since the expandable introducer sheath need not be removed and replacedby a secondary repositioning sheath, the risk of prematuretearing/peeling is essentially eliminated and the risk of shifting theintroduced device inadvertently (e.g., by overuse of force) is reducedor eliminated. Furthermore, allowing the expandable introducer sheath toremain in an insertion path simplifies the process of inserting theintroduced device by reducing the number of steps in the insertionprocedure, e.g. by eliminating a second step where the sheath and valvemust be peeled away or torn before it is removed.

Such an expandable sheath also does away with the need for theconventional set up of having multiple sheaths, such as a peel awayintroducer sheath and a repositioning sheath for the introduction of amedical device (e.g. an intracardiac heart pump) into the vessel opening(e.g. arteriotomy). Such an expandable sheath allows a repositioningsheath to be used in conjunction with it, if necessary, but does notrequire one in all cases. Once the expandable sheath is positioned, itmaintains access to a vessel even after the medical device is removed,should such access be required for other medical procedures. Thisincreases procedural efficiency of any medical procedure as there is noneed to peel away the introducer sheath for the insertion of arepositioning sheath each time access to the vessel opening is required.Furthermore, more accurate repositioning of the medical device can beachieved with the expandable introducer sheath as the expandableintroducer sheath is fixed in position once inserted, whereas theinsertion of a separate repositioning sheath involves multiple stepsthat increase the chances of misplacing the medical device.

The expandable sheath therefore removes the need for multiple sheaths(e.g. an introducer sheath and a repositioning sheath) during anymedical procedure requiring access to an opening of a blood vessel of apatient. In particular, the use of a frame and coating assembly whichcan expand and collapse while being resistant to kinking, and return toits original shape after deformation, advantageously enables deliveryand recovery of the medical device. The consolidation of the introducersheath and the repositioning sheath into a single device can decreasethe costs involved during a medical procedure. Further, since only asingle sheath is required to gain arteriotomic access to a vessel, lessbleeding may be involved during its long-term use with a percutaneousmedical device, such as a heart pump. In addition, configuring theexpandable sheath for compatibility with a dilator assembly and a styletassembly reduces issues with dilator insertion and removal as well asimproves hemostasis performance. Advantageously, the combination of adual-dilator assembly, an expandable sheath and a hemostasis styletprovide a synergistic system which can be used relatively early in aprocedure, e.g. in a catheterization lab rather than later in procedure,e.g. in surgery, when displacement of the pump could have more severeconsequences for a patient. Because the system can be used relativelyearly in a procedure, potential pump migration can be addressed earlier,and vascular injury can be reduced. According to a first implementationof the present disclosure, there is provided an introducer sheathincluding an expandable sheath frame having a length, a first thickness,a proximal end and a distal end. The frame includes strands extendinglongitudinally between the proximal end and the distal end, and havingan exterior surface and an interior surface that form an interior lumenalong the length of the frame. The frame is configured to achieve anexpanded state and a contracted state, the expanded state forming anexpanded cross-section in the lumen for passing a medical devicetherethrough. The frame has a smooth coating about the exterior surfaceand protrusions extending into the lumen along the interior surface.

In some implementations, the cross-section of the expandable sheath bodyis circular. In certain implementations, the cross-section of theexpandable sheath body is elliptical. A sheath having a circularcross-section may have a perimeter of the same length as a sheath havingan elliptical cross-section. In further implementations, thecross-section of a given expandable sheath body may be configured totemporarily change. For example, the introduction of devices into thesheath or the exertion of forces on the sheath may cause thecross-section of the sheath to change between circular and elliptical.Such a temporary change in cross-section advantageously allows for theexpandable sheath to accommodate blood pump elements having largerdiameters, and upon passing them, to return to a cross-section having asmaller area.

In further implementations, the variation in cross-sectional area for anexpandable sheath of a given perimeter or circumference advantageouslyallows for the simultaneous introduction of devices using a hub into thesheath that have larger diameters than devices accommodated by sheathsof an invariable cross-section. For example, an expandable sheath thatis able to accommodate both a blood pump and a catheter could beemployed for percutaneous coronary intervention. Such sheaths allow fordual access of devices by optimizing the space available within theintroducer sheath. Additionally, such implementations involving variablecross-section expandable sheaths allow for a free shape (i.e., a shapeof the expandable sheath within the vasculature of the patient and notcontaining a device) having a small diameter for insertion into thearteriotomy. This allows the arteriotomy to be kept small, as the widthof the sheath is aligned with the formation of the resultingarteriotomy. An elliptical cross-section can also be used for insertioninto the arteriotomy, while keeping the arteriotomy small. Theelliptical cross-section helps to obtain distal flow, as the ellipticalcross-section generally matches the shape of the arteriotomy.Additionally, the incorporation of a small, variable diameter expandablesheath improves hemostasis during procedures. The forces exerted on thevasculature by the sheath in implementations wherein the expandablesheath has a small diameter free shape mimic the way in which bloodvessels naturally stretch, advantageously preventing damage unto thevasculature by the sheath.

In some implementations, the introducer sheath includes a polymer layercovering an outer circumference of the frame and forming the smoothcoating. In some implementations, the polymer layer comprises at leastone of polyether and polyurethane. In certain implementations, thepolyurethane comprises TPU. In some implementations, the TPU has adurometer between about D20 and about D90. In certain implementations,the TPU has a durometer between about D30 and about D80. In furtherimplementations, the TPU has a durometer between about D40 and aboutD70. In some implementations, the TPU has a durometer between about D50and about D60. In further implementations, the TPU has a durometer ofabout D55. In some implementations, the expandable sheath frame has anexpansion mechanism that allows the frame to expand and contract. Incertain implementations, the strands are configured with a bias toexpand or contract from a resting position. According to someimplementations, the expansion mechanism permits the strands to sliderelative to each other when the frame expands and contracts.

In some implementations, the strands include first and secondoverlapping strands, with the second strand extending radially inwardfrom the first strand. In certain implementations, the second strandoverlaps with the first strand and forms a plurality of peaks thatproject into the lumen.

According to certain implementations, the coating extends about theinterior surface. In some implementations, the coating covers theprotrusions along the interior surface. In certain implementations, thecoating covering the protrusions has a first thickness and the coatingextending about the exterior surface has a second thickness. In someimplementations, the first thickness is less than the second thickness.

In certain implementations, the first strand is bounded on an upper sideby the smooth exterior surface coating. In some implementations, thecoating covers the second strand along a first longitudinal side of thesecond strand. According to certain implementations, the coating coversan exterior-facing side of the first strand and an interior facing sideof the second strand.

In some implementations, the frame includes a braided mesh formed offirst strands. In certain implementations, the diameter of the firststrands is between about 1 millimeters and about 10 millimeters. Infurther implementations, the diameter of the first strands is betweenabout 3 millimeters and about 8 millimeters. In some implementations,the diameter of the first strands is between about 5 millimeters andabout 6 millimeters. In further implementations, the diameter of thefirst strands is about 5.5 millimeters. According to certainimplementations, the first strands are wrapped in a spiral directionalong the length. In certain implementations, the frame includes secondstrands. In some implementations, the second strands are wrapped in acounter-clock-wise direction along the length.

According to certain implementations, a thickness of the polymer layeris less than a thickness of the protrusions extending into the lumenalong the interior surface. In some implementations, a thickness of thecoating is less than the thickness of the polymer layer. In certainimplementations, the thickness of the protrusions is less than athickness of a strand of the first strands. In some implementations, thethickness of the protrusions is less than about 75 or 100 μm.

In some implementations, the introducer sheath includes a sheath tip atthe distal end of the expandable sheath frame, the sheath tip having athickness, wherein the sheath tip thickness is greater than thethickness of the expandable sheath frame.

In certain implementations, at least one of the frame, polymer layer,and coating of the sheath tip is thicker than the frame, polymer layer,and coating of the sheath. In some implementations, the sheath tip ispolymer. In certain implementations, the polymer is co-molded with thecoating of the sheath frame. According to certain implementations, thesheath tip is made of a first material and the expandable sheath is madeof a second material different than the first material. In someimplementations, the first material has a different stiffness than thesecond material. In certain implementations, the distal tip of thesheath is stiffer than the proximal end of the sheath.

According to a further implementation of the present disclosure, thereis provided a dilator assembly for the insertion of a medical deviceinto a blood vessel. The dilator assembly includes an inner dilatorhaving a first length and a lumen between proximal and distal ends ofthe inner dilator, and an outer dilator having a second length and alumen between proximal and distal ends of the outer dilator. The outerdilator is coaxial with the inner dilator and the first length isgreater than the second length. The inner dilator and the outer dilatorare configured to be spaced apart radially by a circumferential gaphaving a gap thickness. The inner dilator and outer dilator assembly incombination with the expandable sheath permit stretching of theexpandable sheath into a smaller diameter increased length state, e.g.for insertion of the expandable sheath, without the need for multiplesheaths.

In certain implementations, the inner dilator of the dilator assemblyincludes a shaft extending through the lumen of the outer dilator and adistal tip forming a cavity about the distal end of the inner dilator.In some implementations, the cavity has an inner wall, a closed end, andan open proximal end sized to receive the distal end of the outerdilator. According to certain implementations, the inner wall has adiameter greater than the diameter of the inner dilator shaft. In someimplementations, the distal end of the outer dilator extends axiallyalong the inner wall within the cavity to a position between the closedend and the open proximal end, forming a sheath tip receptacle.

According to certain implementations, the outer dilator of the dilatorassembly includes a proximal portion with a first diameter, a distalportion with a second diameter, and a conical transition portion betweenthe proximal portion and the distal portion. In some implementations,the second diameter is smaller than the first diameter. In certainimplementations, the first diameter of the outer dilator issubstantially equal to an outer diameter of a tip of the inner dilator.

According to a further implementation of the present disclosure, thereis provided a sheath assembly including the introducer sheath and thedilator assembly in combination. In some implementations, the innerdilator and the outer dilator are configured to be inserted into thefirst lumen of the expandable sheath frame to adjust a diameter of theexpandable sheath frame. According to certain implementations, the headof the inner dilator is bonded to the distal end of the dilator.

In some implementations, the second thickness is greater than thethickness of the sheath frame such that the sheath frame fits within thecircumferential gap, the sheath tip fits within the sheath tipreceptacle, and the second thickness is smaller than the thickness ofthe sheath tip such that the sheath tip is retained within the dilatortip.

According to a further implementation of the present disclosure, thereis provided a method of manufacturing an expandable introducer sheath.The method comprises priming a sheath frame using a priming solution.The sheath frame can be primed for adhesion to a polymer layer. Themethod further comprises assembling the polymer layer over the sheathframe. The method further comprises bonding the polymer layer and thesheath frame by exposing the polymer layer and the sheath frame to airfor a duration of time, wherein the air is heated to a firsttemperature. The method further comprises coating an inner surface ofthe polymer layer and the sheath frame with a lubricious material. Insome implementations, the method further comprises coating an outersurface of the polymer layer and the sheath frame with the lubriciousmaterial.

In some implementations, the lubricious material may be hydrophobic. Inother implementations, the lubricious material may be hydrophilic. Incertain implementations, the method further comprises coating the innersurface of the polymer layer and the sheath frame with a hydrophobiclubricious material and coating the outer surface of the polymer layerand the sheath frame with a hydrophilic lubricious material. In someimplementations, the method further comprises coating the inner surfaceof the polymer layer and the sheath frame with a hydrophilic lubriciousmaterial and coating the outer surface of the polymer layer and thesheath frame with a hydrophobic lubricious material.

According to another implementation of the present disclosure, there isprovided an introducer sheath including an expandable sheath body havinga first length, a longitudinal axis, and proximal and distal ends. Theexpandable sheath body includes a first lumen extending between theproximal and distal ends of the expandable sheath body, a braid formingthe first lumen, and a polymer encapsulating at least a distal portionof the braid. The first lumen having a first diameter in a firstelongated state and a second diameter in a second relaxed state, thesecond diameter in the second relaxed state is sized to accommodate themedical device. The braid formed of at least one strand of an elasticmaterial (e.g. a metal) extending from the proximal end of theexpandable sheath body at an acute angle relative to the longitudinalaxis of the expandable sheath body. The polymer can expand or collapsealong with the braid. The acute angle and the material forming the atleast one strand can be selected such that the medical device can bepassed through the expandable sheath body without the expandable sheathbody buckling.

In some implementations, the braid includes first strands wrapped in aclock-wise spiral direction along the first length and second strandswrapped in a counter-clock-wise spiral direction along the first length,which can permit expansion and contraction of the braid while avoiding afinger-trapping effect and/or buckling of the sheath. In someimplementations, the first strands and the second strands areradiopaque. In certain implementations, the diameter of at least one thefirst strands and the second strands is between about 1 millimeters andabout 10 millimeters. In further implementations, the diameter of atleast one of the first strands and the second strands is between about 3millimeters and about 8 millimeters. In some implementations, thediameter of at least one of the first strands and the second strands isbetween about 5 millimeters and about 6 millimeters. In furtherimplementations, the diameter of at least one of the first strands andthe second strands is about 5.5 millimeters. According to certainimplementations, an angle between the first strands and the secondstrands is about 35 degrees, 45 degrees, or 55 degrees. In otherimplementations, the braid includes a braid pattern of the first strandsand the second strands. In some implementations, the braid patterndefines a rhombi, each rhombi including a first corner and a secondcorner adjacent the first corner. According to certain implementations,at least one strand of the first strands goes over at least one strandof the second strands at the first corner and the at least one strand ofthe first strands goes over the at least one strand of the secondstrands at the second corner. In other implementations, at least onestrand of the first strands goes over at least one strand of the secondstrands at the first corner and the at least one strand of the firststrands goes under the at least one strand of the second strands at thesecond corner. The braid and strand configurations enable the sheath tohave sufficient flexibility to expand and contract as needed to insertthe medical device, while having sufficient rigidity to maintain an openlumen and withstand axial forces when the medical device is inserted orwithdrawn.

In certain implementations, the frame material comprises at least one ofNitinol round wire, Nitinol flat wire, Stainless steel round wire,stainless steel flat wire, liquid crystal polymer, polyamide, andpolyether ether ketone (PEEK). In some implementations, the polymerencapsulating the frame comprises at least one of silicone andthermoplastic polyurethane. The frame and encapsulating materialcombination permits the sheath to expand and contract while havingsufficient rigidity to maintain an open lumen and withstand axial forceswhen the medical device is inserted or withdrawn, and permits promotinga smooth flow of blood along the outer surface of the sheath to reducethe risk of clots forming.

In some implementations, the introducer sheath includes a hub having asecond length and a second lumen extending between proximal and distalends of the hub. The distal end of the hub can be bonded or attached tothe proximal end of the expandable sheath body. The second lumen of thehub can be in communication with the first lumen of the sheath. Infurther implementations, the hub includes a hemostasis valve within thesecond lumen, the hemostasis valve being configured for insertion of acomponent. In other implementations, the hub includes a side-arm thatallows for flushing and aspiration of the introducer sheath. The hub andvalve configuration prevent blood from leaking outside of the patientduring insertion and/or removal of the device, and also provide astructural anchor to minimize the risk of sheath eversion at the hub.

According to certain implementations, the polymer encapsulates theentire braid. In other implementations, the introducer sheath includes ahydrophilic material coating at least a portion of an inner surface ofthe polymer. In some implementations, the hydrophilic material coats atleast a portion of an outer surface of the polymer. The hydrophiliccoating on the inner surface of the polymer permits a reduction of thefrictional forces during delivery of the medical device and to avoidclotting by allowing adequate blood flow along the sheath body. Incertain implementations, the inner surface of the polymer has a smoothsurface and the outer surface of the polymer has at least one trough. Inother implementations, the inner surface of the polymer has at least onetrough and the outer surface of the polymer has a smooth surface.

In certain implementations, the proximal end of the expandable sheathbody lies outside of a body of a patient. In other implementations, theintroducer sheath is configured for the insertion of a blood pump into ablood vessel.

In some implementations, the introducer sheath includes at the distalend of the expandable sheath body a distal portion of the first lumen,the distal portion shaped to reversibly lock with a distal end of adilator. In other implementations, the distal portion allows movementwith respect to the dilator in one direction but not the other. Thedistal portion of the introducer sheath locking with the distal end ofthe dilator permits stretching of the introducer sheath relative to ananchor point.

According to a further implementation of the present disclosure, thereis provided a dilator assembly for the insertion of a medical deviceinto a blood vessel. The dilator assembly includes an inner dilatorhaving a first length and a first lumen between proximal and distal endsof the inner dilator, an outer dilator having a second length and asecond lumen between proximal and distal ends of the outer dilator, anda hub attachment having a third length and a third lumen betweenproximal and distal ends of the hub attachment. The outer dilator can beaxially aligned with the inner dilator and the first length can begreater than the second length. The inner dilator and the outer dilatorare configured to be inserted into an expandable sheath of an introducerassembly to adjust a diameter of the expandable sheath. The hubattachment can be axially aligned with the outer dilator and the outerdilator can lie within the third lumen. The distal end of the hubattachment can be attached to a proximal end of the introducer assembly.In further implementations, adjusting the diameter of the expandablesheath comprises changing the diameter from a first diameter in a firstrelaxed state to a second diameter in a second expanded state. The innerdilator and outer dilator assembly in combination with the expandablesheath permit stretching of the expandable sheath into a smallerdiameter increased length state, e.g. for insertion of the expandablesheath, without the need for multiple sheaths.

In some implementations, the dilator assembly includes a luer assemblyhaving a fourth length and a fourth lumen between proximal and distalends of the luer assembly. The distal end of the luer assembly can bebonded to the proximal end of the hub attachment. In certainimplementations, the luer assembly comprises a compressible elastomerand a compression nut. In other implementations, the compressibleelastomer includes a first state and a second state. The first statecorresponds to minimum compression and the second state corresponds tomaximum compression. In some implementations, the compression nut isloose and the compressible elastomer is in the first state, allowing thehub attachment to traverse with respect to the outer dilator. In certainimplementations, the compression nut is tight and the compressibleelastomer is in the second state, allowing the hub attachment to remainin place with respect to the outer dilator.

In other implementations, the distal end of the inner dilator is bondedto a tip and the proximal end of the inner dilator is bonded to a luerhub. In certain implementations, the inner dilator lies within the outerdilator such that the proximal and distal ends of the inner dilator areexposed. In some implementations, the hub attachment comprises a hubattachment cap at the distal end of the hub attachment.

According to a further implementation of the present disclosure, thereis provided a hemostasis stylet assembly for controlling hemostasis witha blood vessel. The hemostasis stylet assembly includes a locking hubhaving distal and proximal ends, a hemostasis stylet hub having a lumenbetween distal and proximal ends of the hemostasis stylet hub, a firststerile layer having a first length and a first lumen between distal andproximal ends of the first sterile layer, a hemostasis stylet bodyhaving distal and proximal ends, and a second sterile layer having asecond length and a second lumen between distal and proximal ends of thesecond sterile layer. The distal end of the locking hub can beconfigured to attach to a proximal end of an introducer assembly. Thefirst sterile layer and a hemostasis stylet body can be attached to thedistal end of the hemostasis stylet hub. The second sterile layer can beattached to the proximal end of the hemostasis stylet hub. The distalend of the first sterile layer can be attached to the locking hub. Thedistal end of the hemostasis stylet body can be configured to beinserted into an expandable sheath of the introducer assembly in orderto control hemostasis between the expandable sheath and an opening of ablood vessel. The hemostasis stylet, in combination with the dualdilator assembly and the expandable sheath allows for control of theblood flow along the expandable sheath, to reduce potential ischemia. Insome implementations, the hemostasis stylet can be a repositioningsheath, which is also used to control of the blood flow along theexpandable sheath and minimize bleeding.

In some implementations, the locking hub has a first state correspondingto buttons in a compressed state and a second state corresponding to thebuttons in an uncompressed state. In certain implementations, thelocking hub in the first state allows the locking hub to be movable withrespect to the hemostasis stylet hub. In other implementations, thelocking hub in the second state allows the locking hub to be in a fixedstate with respect to the hemostasis stylet hub. In furtherimplementations, the locking hub includes a locking cap at the distalend of the locking hub.

In other implementations, the first sterile layer includes a firstattachment component attached to the proximal end of the locking hub. Incertain implementations, the second sterile layer includes a secondattachment component attached to the proximal end of the hemostasisstylet hub. In some implementations, the proximal end of the hemostasisstylet hub is attached to an internal seal component.

According to a further implementation of the present disclosure, thereis provided an introducer sheath including an expandable sheath bodyhaving a first length, a longitudinal axis, and proximal and distalends. The expandable sheath body includes a first lumen extendingbetween the proximal and distal ends of the expandable sheath body, abraid forming the first lumen, and a polymer encapsulating at least aportion of the braid. The first lumen having a first diameter in a firstelongated state, the first diameter in the first relaxed state is sizedto insert the introducer sheath into a vessel, a second diameter in asecond relaxed state, and a third diameter in a third expanded state,the third diameter in the expanded state sized to accommodate themedical device. The braid formed of at least one strand extending fromthe proximal end of the expandable sheath body at an acute anglerelative to the longitudinal axis of the expandable sheath body. Thepolymer can expand or collapse along with the braid. Selection of theacute angle and the material of the at least one strand can permit themedical device to pass through the expandable sheath body in its thirdexpanded state without the expandable sheath body buckling.

According to a further implementation of the present disclosure, thefirst lumen has a first diameter in a first relaxed state and a seconddiameter in a second expanded state, the second diameter in the secondexpanded state being sized to accommodate the medical device. The acuteangle and the material can be selected to allow the medical device topass through the expandable sheath body, and the expandable sheath bodywill expand to its second expanded state to accommodate the medicaldevice.

According to a further implementation of the present disclosure, thereis provided a sheath assembly for the insertion of a medical device intoa blood vessel. In some implementations, the sheath assembly includes anintroducer sheath and a dilator assembly. In other implementations, thesheath assembly includes an introducer sheath and a hemostasis styletassembly. In certain implementations, the sheath assembly includes anintroducer sheath, a dilator assembly, and a hemostasis stylet assembly.The introducer sheath, dilator assembly and hemostasis stylet assemblypermit insertion and withdrawal of a medical device in the introducersheath without the sheath buckling, while keeping the opening requiredin a vessel to a minimum, and controlling leak path blood flow.

According to a further implementation of the present disclosure, thereis provided a method of inserting a pump into a blood vessel. The methodcomprises attaching an introducer assembly to a dilator assembly. Theintroducer assembly comprises an expandable sheath having a firstdiameter and a first length. The method further comprises moving thedilator assembly with respect to the introducer assembly in the proximaldirection such that the expandable sheath of the introducer assemblycontracts to a second diameter and a second length, the second diameterbeing smaller than the first diameter and the second length beinggreater than the first length. The method further comprises insertingthe introducer assembly and the dilator into a desired location in ablood vessel such that an opening of the blood vessel expands toaccommodate the second diameter of the expandable sheath. The methodfurther comprises moving the dilator assembly with respect to theintroducer assembly in the distal direction such that the expandablesheath of the introducer assembly expands to a third diameter and athird length, and the opening of the blood vessel expands to accommodatethe third diameter of the expandable sheath, the third diameter beinggreater than the second diameter and the third length being smaller thanthe second length. The method further comprises detaching the dilatorassembly from the introducer assembly and removing the dilator assemblyfrom the desired location in the blood vessel. The method furthercomprises inserting a pump through the introducer assembly such that theexpandable sheath expands to a fourth diameter to accommodate the pumpas the pump traverses within the introducer assembly, and the opening ofthe blood vessel expands to accommodate the fourth diameter of theexpandable sheath, the fourth diameter being greater than the thirddiameter. The method further comprises inserting a hemostasis styletthrough the introducer assembly such that the expandable sheath expandsto a fifth diameter to accommodate the hemostasis stylet as thehemostasis stylet traverses within the introducer assembly, the fifthdiameter being such as to achieve hemostasis between the opening of theblood vessel and the expandable sheath. The method of inserting thepump, including the introducer sheath, dilator assembly and hemostasisstylet assembly permits insertion of the medical device in theintroducer sheath without the sheath buckling, while keeping the openingrequired in a vessel to a minimum, and controlling leak path blood flow.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other objects and advantages will be apparent uponconsideration of the following detailed description, taken inconjunction with the accompanying drawings, in which like referencecharacters refer to like parts throughout, and in which:

FIGS. 1A and 1B show an isometric view of an illustrative sheathassembly including an illustrative expandable sheath coupled to anillustrative dilator assembly, and an illustrative expandable sheathcoupled to a hemostasis stylet assembly, respectively;

FIG. 2 shows an isometric view of an illustrative expandable sheathassembly;

FIG. 3 shows the introducer sheath after insertion into the bloodvessel;

FIGS. 4A and 4B show schematic cross-sectional profiles of an expandablesheath having elongated, relaxed and expanded states;

FIG. 5 shows an isometric view of a pump insertion through an expandablesheath;

FIG. 6 shows an isometric view of a pump partially removed from anillustrative expandable sheath;

FIGS. 7A and 7B show illustrative braid patterns for an illustrativeexpandable sheath body;

FIG. 8 shows an isometric view of an illustrative introducer sheath bodywith pairs of opposed threads in a first pattern;

FIG. 9 shows an illustrative view of a braid of an expandable sheathwith opposed threads in a second pattern;

FIG. 10 shows an illustrative view of a laser cut frame for anillustrative expandable sheath;

FIGS. 11A-C show an illustrative view of a single wire frame for anillustrative expandable sheath;

FIG. 12 shows an illustrative view of a braid of an expandable sheathhaving a first portion in a relaxed state and a second portion in anexpanded state;

FIGS. 13A and 13B show isometric views of braid manufacturing stages;

FIGS. 14A to 14C show isometric views of braid manufacturing stages;

FIG. 15 shows an illustrative method for manufacturing the expandablesheath assembly of FIG. 2 ;

FIG. 16 shows an illustrative expandable sheath body comprising a braid,a polymer, and a hydrophilic coating;

FIG. 17 shows a cross-section of the expandable sheath bodydemonstrating the braid material surrounded by the polymerencapsulation;

FIG. 18 shows a cross-section of the braid material surrounded by thepolymer encapsulation;

FIG. 19 shows an illustrative method for inserting a medical device intoa vessel opening using the illustrative sheath assembly of FIG. 1 ;

FIG. 20 shows an illustrative view of a dilator assembly;

FIG. 21 shows an illustrative view of an introducer sheath and dilatorassembly;

FIGS. 22A and 22B show isometric views of the expandable sheath assemblyof FIG. 2 in a relaxed or resting state;

FIG. 23A shows an isometric view of a sheath tip interlock for inner andouter dilators of the dilator assembly;

FIG. 23B shows an isometric view of an exemplary dilator tip to sheathconnection;

FIG. 24A shows an isometric view of a released dilator tip to sheathconnection in a first state;

FIG. 24B shows an isometric view of a released dilator tip to sheathconnection;

FIG. 25A shows an isometric view of a dilator removal distalpreparation;

FIG. 25B shows an isometric view of a dilator removal distalpreparation;

FIG. 25C shows an isometric view of a dilator being removed through theexpandable sheath body;

FIG. 26 shows a cross-section view of an illustrative sheath tip;

FIG. 27 shows a cross-section view of an illustrative sheath tip;

FIG. 28 shows a cross-section view of an illustrative sheath tip;

FIG. 29 shows a cross-section view of an illustrative sheath tip;

FIG. 30 shows a cross-section view of an illustrative sheath tip;

FIG. 31 shows a cross-section view of an illustrative sheath tip;

FIG. 32 shows a cross-section view of an illustrative sheath tip;

FIG. 33 shows a cross-section view of an illustrative sheath tip;

FIGS. 34A and 34B show cross-section views of an illustrative dilatortip configuration;

FIGS. 35A and 35B show cross-section views of an illustrative dilatortip configuration;

FIGS. 36A and 36B show cross-section views of an illustrative dilatortip configuration;

FIGS. 37A and 37B show cross-section views of an illustrative dilatortip configuration;

FIGS. 38A and 38B show cross-section views of an illustrative sheathcapture configuration;

FIGS. 39A and 39B show cross-section views of an illustrative sheathcapture configuration;

FIGS. 40A and 40B show cross-section views of an illustrative sheathcapture configuration;

FIGS. 41A and 41B show cross-section views of an illustrative sheathcapture configuration;

FIG. 42 shows a cross-section view of the distal tip shown in FIG. 29with a dilator tip interlock;

FIGS. 43A to 43C show isometric views of illustrative hub components ofthe expandable sheath assembly;

FIG. 44 shows a cross-section view of an illustrative hub;

FIG. 45 shows a cross-section view of an illustrative hub with supportfingers;

FIG. 46 shows an isometric view of an illustrative hemostasis styletassembly;

FIG. 47 shows an isometric view of an illustrative hemostasis styletassembly;

FIG. 48 shows an isometric view of an illustrative hemostasis styletassembly;

FIG. 49 shows a cross-section of the braid material surrounded by thepolymer encapsulation forming a textured outer surface and a smoothinner surface;

FIG. 50 shows a cross-section of the braid material surrounded by thepolymer encapsulation forming a smooth outer surface and a smooth innersurface;

FIG. 51 shows a cross-section of the braid material surrounded by thepolymer encapsulation forming a smooth outer surface and a texturedinner surface;

FIG. 52 shows a cross-section of the braid material surrounded by acoating and having a smooth outer surface and a textured inner surface;

FIG. 53 shows the results of thrombogenicity testing on a first testexpandable sheath having a cross-section as shown in FIG. 49 ;

FIG. 54 shows the results of thrombogenicity testing on a second testexpandable sheath having a cross-section as shown in FIG. 47 ;

FIG. 55 shows a cross-section of the braid material surrounded by thepolymer encapsulation;

FIG. 56 shows a cross-section of the braid material surrounded by thepolymer encapsulation;

FIG. 57 shows an illustrative method for manufacturing the expandablesheath of FIG. 2 ;

FIG. 58 shows an illustrative method for manufacturing the expandablesheath of FIG. 2 using a polymer solvent solution;

FIG. 59 shows an isometric view of the expandable sheath system of FIG.21 ;

FIG. 60 shows an isometric view of an illustrative delivery system andsheath hub;

FIG. 61 shows an isometric view of an illustrative sheath hub;

FIG. 62 shows an isometric view of an illustrative sheath hub;

FIG. 63 shows a cross-section of an illustrative sheath hub;

FIG. 64 shows a cross-section of an illustrative sheath system tip;

FIG. 65 shows a cross-section of an illustrative sheath system tip in afirst position;

FIG. 66 shows a cross-section of an illustrative sheath system tip in asecond position;

FIG. 67 shows a cross-section of an illustrative sheath system tip in athird position;

FIG. 68 shows a cross-section of an illustrative sheath system tip in afourth position;

FIG. 69 shows a cross-section of an illustrative sheath system tip in afifth position;

FIG. 70 shows a cross-section of an illustrative sheath delivery systemin a first position;

FIG. 71 shows a cross-section of an illustrative sheath delivery systemin a first position;

FIG. 72 shows a cross-section of an illustrative sheath delivery systemin a second position;

FIG. 73 shows a cross-section of an illustrative sheath delivery systemin a second position;

FIG. 74 shows a cross-section of an illustrative sheath delivery systemin a third position;

FIG. 75 shows a proximal view of the expandable sheath system;

FIG. 76 shows a cross-section of an illustrative sheath delivery systemin a third position;

FIG. 77 shows a cross-section of an illustrative sheath delivery systemin a third position;

FIG. 78 shows a cross-section of an illustrative sheath delivery systemin a fourth position;

FIG. 79 shows a cross-section of an illustrative sheath delivery systemin a fourth position;

FIG. 80 shows a cross-section of an illustrative sheath delivery systemin a fourth position;

FIG. 81 shows a cross-section of an illustrative sheath delivery systemin a fifth position;

FIG. 82 shows an isometric view of an illustrative sheath deliverysystem;

FIG. 83A shows a cross-sectional view of an illustrative sheath deliverysystem in a first position;

FIG. 83B shows a cross-sectional view of an illustrative sheath deliverysystem in a second position;

FIG. 84A shows a cross-sectional view of an illustrative sheath deliverysystem;

FIG. 84B shows a cross-sectional view of an illustrative sheath deliverysystem;

FIG. 85A shows a view of an illustrative luer-blocking mechanism;

FIG. 85B shows a second view of a luer-blocking mechanism;

FIG. 86A shows a first cross-sectional view of the hub housing of anillustrative sheath delivery system;

FIG. 86B shows a first aerial cross-sectional view of the hub housing ofan illustrative sheath delivery system;

FIG. 86C shows second a cross-sectional view of the hub housing of anillustrative sheath delivery system;

FIG. 86D shows a second aerial cross-sectional view of the hub housingof an illustrative sheath delivery system;

FIG. 87 shows an illustrative view of a delivery mechanism tip;

FIG. 88 shows a cross-sectional view of an illustrative sheath deliverysystem in a third position;

FIG. 89 shows an illustrative view of a delivery mechanism tip;

FIG. 90 shows a cross-sectional view of an illustrative sheath deliverysystem in a fourth state;

FIG. 91 shows an illustrative cross-sectional view of the hub housing ofan illustrative sheath delivery system;

FIG. 92 shows an illustrative internal view of the hub housing of anillustrative sheath delivery system;

FIG. 93A shows an illustrative cross-sectional view of the hub housingof an illustrative sheath delivery system;

FIG. 93B shows an illustrative cross-sectional view of the hub housingof an illustrative sheath delivery system;

FIG. 94A shows a first isometric view of an illustrative sheath deliverymechanism;

FIG. 94B shows a second isometric view of an illustrative sheathdelivery mechanism;

FIG. 94C shows a first isometric view of a hub and a hub housing of anillustrative sheath delivery mechanism;

FIG. 94D shows a second isometric view of a hub and a hub housing of anillustrative sheath delivery mechanism;

FIG. 95 shows an illustrative barrel of a sheath delivery mechanism;

FIG. 96A shows a first isometric view of an illustrative hub releasedrum of a sheath delivery mechanism;

FIG. 96B shows a second isometric view of illustrative hub release drumof a sheath delivery mechanism; and

FIG. 96C shows an illustrative hub release drum of a sheath deliverymechanism.

DETAILED DESCRIPTION

To provide an overall understanding of the systems, method, and devicesdescribed herein, certain illustrative embodiments will be described.Although the embodiments and features described herein are specificallydescribed for use in connection with an intracardiac heart pump system,it will be understood that all the components and other featuresoutlined below may be combined with one another in any suitable mannerand may be adapted and applied to other types of medical devices such aselectrophysiology study and catheter ablation devices, angioplasty andstenting devices, angiographic catheters, peripherally inserted centralcatheters, central venous catheters, midline catheters, peripheralcatheters, inferior vena cava filters, abdominal aortic aneurysm therapydevices, thrombectomy devices, TAVR delivery systems, cardiac therapyand cardiac assist devices, including balloon pumps, cardiac assistdevices implanted using a surgical incision, and any other venous orarterial based introduced catheters and devices.

The systems, methods and devices described herein provide an expandablesheath assembly for the insertion of a medical device (e.g., anintracardiac heart pump) into a blood vessel through a vessel aperture.The expandable sheath assembly comprises a dilator assembly and a sheathbody having an inner surface and an outer surface, the inner surfacedefining a lumen that extends between proximal and distal ends of thesheath. Optionally, the expandable sheath assembly may include ahemostasis stylet. The expandable sheath assemblies (including thesheath body, dilator assembly, and optional hemostasis stylet) areespecially advantageous over existing expandable sheath assemblies forpatients with coronary artery disease (CAD) and peripheral arterydisease, presenting with calcification and tortuosity of arteries,making delivery of introducer sheaths and catheters difficult. Theexpandable sheath assemblies herein are easier to insert thantraditional assemblies because of their reduced insertion profile,increased flexibility, reduced friction, and reduced risk of kinkingunder loads. The reduced insertion profile minimizes insertion relatedcomplications, minimizes stretching and load on the vessel opening, andminimizes the risk of limb ischemia. The structure of the sheath bodydescribed herein provides sufficient axial stiffness for pushability andbuckling resistance, while maintaining bending flexibility and kinkresistance, reduces frictional force to prevent “finger trapping.”Moreover, the structures of the sheath body described herein provides animprovement over existing introducer sheaths bodies by either, having asmooth inner surface with a thin coating thickness reducing the forcerequired to expand the sheath compared to the force required to expandthe sheath having a coating without any bias, or having a smooth outersurface reducing the risk of thrombus formation during use over longerdurations while at the same time enabling the sheath to expand andcontract as desired and reducing friction between the sheath body anddevices being inserted through it. Furthermore, the structure of thesheath body described herein interfaces with a dilator assembly, suchthat the sheath body can be held in place for insertion into a bodylumen by having a portion of the sheath body be constrained or entrappedin a longitudinal direction. This constraint or entrapment of the sheathbody facilitates the expandable sheath body insertion in combinationwith a dilator assembly, without damaging the expandable sheath body oraltering its properties.

The sheath body can expand between different states to accommodate themedical device. For example, the sheath body is elongated in a firstsmaller diameter state for insertion and relaxed into a second largerdiameter state once at a desired location to allow the passage of aportion of a medical device through the lumen, the portion of themedical device having a transverse cross-sectional area larger than atransverse cross-sectional area of the lumen in the first state. Indifferent configurations, the sheath is further expanded between aresting state when the sheath is at its desired location, and a largerdiameter state when the medical device is passed through. In anyconfiguration, the expandable sheath assemblies herein do not requireadditional elements relative to a standard introducer: no externalballoon, no fold in the expandable sheath body, no second sheath fordelivery. This can be advantageous over existing expandable sheathassemblies by simplifying the use of the expandable sheath assembly(e.g. requiring less steps, taking less time).

Moreover, the momentary expansion of the sheath body from the elongatedstate to the relaxed state (or from the relaxed state to the expandedstate) minimizes the size of the opening, e.g. arteriotomy, requiredwhen inserting the sheath into the vasculature of the patient.Minimizing the amount of time the sheath body is in the expanded statealso minimizes damage to a vessel wall as a smaller opening would berequired to accommodate the sheath body in the relaxed or collapsedstate, thereby minimizing thrombotic occlusion of the vessel. A smalleropening also minimizes the time to reach hemostasis after removal of themedical device. Such an expandable sheath does away with the need forthe conventional set up of having multiple sheaths, such as a peel awayintroducer sheath and a repositioning sheath for the introduction of amedical device (e.g. an intracardiac heart pump) into the vessel. Suchan expandable sheath also allows such a conventional set-up to be usedin conjunction with it, if necessary. Once the expandable sheath ispositioned in an opening of a blood vessel of a patient, it maintainsaccess to the vessel even after the medical device is removed, shouldsuch access be required for other medical procedures. This increasesprocedural efficiency of any medical procedure as there is no need tore-gain alternative access or re-insert a second sheath in the sameaccess site. The effective consolidation of the introducer sheath andthe repositioning sheath into a single device decreases the costsinvolved during a medical procedure. Further, since only a single sheathis required to gain arteriotomic access to a vessel, less bleeding wouldbe involved during long term use of a percutaneous medical device suchas a heart pump. The integration of the sheath body and dilator assemblywith the hemostasis stylet allows for titrated hemostasis at the vesselopening. In some implementations, the hemostasis stylet can be arepositioning sheath, which is also used to control of the blood flowalong the expandable sheath and minimize bleeding.

Additionally, the expandable sheath assemblies herein are advantageousover existing expandable sheath assemblies because they maintainguidewire access throughout the full procedure by always allowing theuser to remove the pump with the sheath in place.

FIGS. 1-6 show different aspects of an illustrative sheath assembly, andexemplary components and configurations. FIG. 1A shows an illustrativesheath assembly including an expandable introducer sheath 200 (furtherdescribed in relation to FIG. 2 ) coupled to a dilator assembly 2000(further described in relation to FIG. 20 ). FIG. 1B shows theillustrative sheath assembly of FIG. 1A with the expandable introducersheath 200 coupled to a hemostasis stylet assembly 4600 (furtherdescribed in relation to FIG. 46 ). As described further below inrelation to FIG. 19 , the expandable introducer sheath 200 is attachedto the dilator assembly 2000 prior to insertion into a desired locationin blood vessel. After the expandable introducer sheath 200 and dilatorassembly 2000 are at the desired location in the blood vessel, thedilator assembly is removed from the blood vessel, and a medical device,e.g. a pump, is introduced through the expandable introducer sheath 200.After the medical device, e.g. the pump, has been introduced, thehemostasis stylet assembly 4600 can be coupled to the expandableintroducer sheath 200 as shown in FIG. 1B to further control anyretrograde bleeding. In some implementations, the hemostasis stylet canbe a repositioning sheath, which is also used to control of the bloodflow along the expandable sheath and minimize bleeding.

FIG. 2 shows an illustrative expandable introducer sheath 200 (e.g. theexpandable introducer sheath 200 of FIG. 1 ), comprising a hub 204 andexpandable sheath body 202. As discussed further below in relation toFIGS. 16-18 and 49-52 , the expandable sheath body 202 of the expandableintroducer sheath 200 comprises a frame and one or more coatings. In oneembodiment, the expandable sheath body 202 includes the frame, a polymercoating encapsulating the frame, and a hydrophilic coating on a portionof an inner surface and/or outer surface of the polymer-coated frame.The frame of the expandable sheath body 202 shown in FIG. 2 may be abraid, for example a woven braid (e.g. FIGS. 7A-B, FIG. 8 , FIG. 9 ), alaser cut frame (e.g. FIG. 10 ), or a wire-wound frame (e.g. FIGS.11A-C). Each of these frames is further described below. Alternatively,the frame of the expandable sheath body 202 may use any other structuresuch that the force to insert a device within the sheath body isminimized (e.g. below 5N), and such that the sheath can turn corners asrequired by patient anatomy (e.g. turn corners with a minimum bendconfiguration of 30 mm through 55-degree bend using a force less than5N). At least one advantage of the hydrophilic coating is to reducefrictional forces on the sheath below a threshold that begins theprocess of “finger trapping”, during which the device being inserted(e.g. an intracardiac heart pump) creates a positive feedback loop, dueto the axial load caused by friction, wherein the sheath will compressupon the device being inserted and increase the frictional force andaxial load resulting in the inserted device becoming seized andinsertion not being able to be completed.

As shown in FIG. 2 , the expandable sheath body 202 is defined by aproximal end 208, a distal end 210, and a lumen extending throughbetween the proximal and distal end. On the proximal end 208, theexpandable sheath body 202 is attached to the hub 204. The hub 204comprises a proximal end and a distal end, with a lumen extendingbetween the proximal end and the distal end. On its distal end, the hub204 is attached to the expandable sheath body 202. On the proximal sideof the hub 204 there is a hemostasis valve 206 within the sheath hub204. The hemostasis valve 206 allows for insertion of components throughthe hub and sheath but prevents flow of fluid (i.e. blood) from thedistal end of the expandable sheath body 202 to the outside of theexpandable sheath body 202 and hub 204. The hub 204 contains a side-arm(not shown in FIG. 2 ) that allows for aspiration of fluid and flushingof the sheath. The distal end 210 of the expandable sheath body 202, asshown in FIGS. 26-33 and described below in relation to FIGS. 26-33 ,has a geometry configured to interface with a dilator assembly (e.g.dilator assembly 2000 of FIG. 20 ). The distal end 210 of the expandablesheath body 202 is also advantageously atraumatic—to avoid damaging theblood vessel wall or any other anatomy during insertion of theexpandable introducer sheath assembly, and while the expandableintroducer sheath assembly remains within a patient.

FIG. 3 shows an illustrative expandable introducer sheath 200 (e.g.expandable introducer sheath 200 shown in FIG. 2 ) after insertion intothe blood vessel 304 of a patient. As shown, the proximal portion 306 ofthe introducer sheath 200 is outside the skin 302 of the patient, whilethe distal portion 308 of the expandable introducer sheath 200 is withinthe vessel 304. As described further below in relation to FIGS. 16-18and 49-52 , at least a distal portion (e.g. portion 308) of theexpandable introducer sheath 200 is coated with one or more coatings.Alternatively, the entire length of the expandable introducer sheath 200is coated with one or more coatings. At least one advantage of theexpandable introducer sheath 200 being coated includes minimizingfriction between various materials of the sheath and the device beinginserted. At least another advantage of the expandable introducer sheath200 being coated and forming a closed-cell mesh is that the expandablesheath is not porous and blood is not diverted through the expandablesheath. At least another advantage of the expandable introducer sheath200 being coated and forming a closed-cell mesh is that, when flushingthe sheath from the sheath hub to clear the entire length of the sheath,the fluid goes along the entire length of the sheath rather than goingthrough the mesh. At least another advantage of the expandableintroducer sheath 200 being coated and forming a closed-cell mesh isthat the expandable introducer sheath 200 is less sensitive topositioning relative to the arteriotomy because the closed-cell meshreduces risk of bleeding across the arteriotomy. At least someadditional advantages of the expandable sheath body (e.g. expandablesheath body 202 of FIG. 2 ) in the expandable introducer sheath 200include providing sufficient stiffness for the sheath body to maintainan open lumen along its length, while remaining flexible enough toexpand, as described below in relation at least to FIGS. 12 and 4 . Inany instances where the medical device being passed through the sheathis an intracardiac heart pump with a pigtail at its distal end, thepigtail has the potential to catch on a distal end of the sheath as thepump is being withdrawn. At least an additional advantage of theexpandable sheath body is to have enough longitudinal resistance orcolumn strength to counter the removal force and prevent the sheath frombuckling and bunching up along its length during removal of the device.

As mentioned above after the expandable introducer sheath 200 is at adesired position in a vessel, a medical device, e.g. a pump, isintroduced into and passes through the expandable introducer sheath 200until the medical device is positioned distal of the expandableintroducer sheath. At a later time the medical device may be in turnpassed through the expandable introducer sheath in order to be withdrawnfrom the body of the patient. The expandable sheath body 202 of theexpandable introducer sheath is designed to expand and contract toaccommodate insertion and withdrawal of the medical device whileavoiding buckling and/or kinking of the expandable introducer sheath.The structure of the sheath body allows for the sheath to expand duringthe passage of the medical device in the lumen of the sheath body.

The expandable introducer sheath can expand between an elongated state,a relaxed state and an expanded state according to at least threedifferent configurations. FIGS. 4A and 4B show schematic profiles of anexpandable sheath body (e.g. the expandable sheath body 202 shown inFIG. 2 ) transitioning between these states. The sheath body must beimpermeable to blood through all expansion states. An elongated state isdefined as a state in which tensile forces are applied to the expandableintroducer sheath, such that the expandable sheath body is stretched,increasing in length and decreasing in diameter. A relaxed state isdefined as a state the expandable introducer sheath is in when noexternal forces are applied to the expandable introducer sheath, e.g. notensile forces, and or no radially expanding or compressing forces. Anexpanded state is defined as one in which radially outward forces may beapplied to the expandable introducer sheath, such that its diameterincreases. In some instances the expandable introducer sheath may alsobe in a second relaxed state, defined as a state in which the diameterof the expandable introducer sheath is reduced relative to a previousstate.

In a first configuration, the expandable introducer sheath is insertedto a desired location in a first state, and the expandable introducersheath relaxes to a second state. As shown for example in FIG. 4A,portion 402 of the sheath is in an elongated first state, whereasportion 404 of the sheath is in a second relaxed state. In the firststate the expandable introducer sheath is stretched, increasing inlength and decreasing in diameter relative to the second state—thediameter of portion 402 of the sheath is smaller than the diameter ofthe sheath in portion 404. Once the expandable introducer sheath is atthe desired location and tensile forces are no longer applied to theexpandable introducer sheath, the expandable introducer sheath relaxesto the second state, a resting state, with a diameter which issufficiently large to allow passage of a medical device, e.g. a pumpwithout further deformation. The diameter of portion 404 in FIG. 4A isgreater than a diameter of a medical device.

In a second configuration, the expandable introducer sheath is insertedto a desired location in a first state, relaxes to a second state, andexpands to a third state to accommodate a medical device. As shown forexample in FIG. 4A, portion 402 of the sheath is in an elongated state,whereas portion 404 of the sheath is in a relaxed state. In turn, asshown in FIG. 4B, portion 406 of the sheath is in an expanded state. Inthe first state, similar to the first configuration, the expandableintroducer sheath is stretched, increasing in length and decreasing indiameter relative to the second state. Once the expandable introducersheath is at the desired location and the expandable introducer sheathis no longer stretched (tensile forces are no longer applied to theexpandable introducer sheath), the expandable introducer sheath relaxesto the second state, a resting state, with a diameter which is largerthan the diameter of the expandable introducer sheath in the firststate, but smaller than a diameter of the medical device to be inserted.In this configuration, a diameter of a medical device to be insertedwould be larger than a diameter of the expandable introducer sheath inits relaxed state, i.e. larger than a diameter of portion 404 of theexpandable introducer sheath in FIG. 4B. In the third state, theexpandable introducer sheath expands further as the larger-diametermedical device is inserted, and expands to accommodate the medicaldevice.

In a third configuration, the expandable introducer sheath is insertedto a desired location in a first state, a resting state, and expands toa second state to accommodate the medical device. The expandableintroducer sheath expands to a larger diameter in the second state. Asshown for example in relation to FIG. 4B, the diameter of portion 404 ofthe sheath in its first resting state is smaller than the diameter ofportion 406 of the sheath in its second expanded state, and the diameterof portion 406 would accommodate the diameter of a medical device to beinserted. At least one advantage of these configurations is that theyallow for a small insertion profile which minimizes insertion relatedcomplications and minimizes stretching and load on the access openingformed in the blood vessel.

In some configurations in each state the sheath has a constant diameteralong its length. In some configurations in any state the sheath mayhave a diameter which varies along its length. For example, in a relaxedstate the expandable sheath body may have a larger diameter in theproximal portion and a smaller diameter in the distal portion with ataper between the larger diameter and the smaller diameter.

As an example, FIG. 5 shows the insertion of a heart pump 502 through anintroducer sheath 200 in the third configuration. As shown in FIG. 5 ,the outer diameter of the pump 502 is larger than the inner diameter ofthe expandable sheath body 202 causing the expandable sheath body 202 toexpand as the pump passes through—the sheath 202 is in an expandedsecond state over the length of the pump 502. The outer diameter ofcatheter 504 may be larger than the inner diameter of the expandablesheath body 202, where the expandable sheath body 202 collapses backdown on the catheter 504 (e.g. in a second relaxed state) after passageof the pump 502 and the expandable sheath body 202 tight on the catheter504 in this second relaxed state. As an example, FIG. 6 shows theremoval of the pump 502. The distal end of the introducer sheath 200expands as the pump 502 is pulled through. The introducer sheath 200must have enough column strength to resist buckling due to thefrictional loads of the pump 502 and of the uncurl force of the pigtail.

As mentioned above, the frame component of the expandable sheath bodymay be at least one of a braid (e.g. FIGS. 7A-B, FIG. 8 , FIG. 9 ), alaser cut frame (e.g. FIG. 10 ), or a wire-wound frame (e.g. FIGS.11A-C). In one embodiment, the frame component of the expandable sheathbody 202 is a braid, e.g. as shown in FIG. 7 . The braid may comprisethreads of braid material that form a pattern. A braid is defined hereinas an interlace of two or more strands or threads, with the two or morestrands or threads crossing each other at least once along a length ofthe braid. In contrast to a mesh, in which connection points are fixed,the crossings between threads in the braid are not fixed, i.e. thecrossings between threads may shift along the length of the braid,and/or the angles of the threads at the crossing may vary as well. Someexamples of the braid material include Nitinol round wire, Nitinol flatwire, stainless steel round wire, stainless steel flat wire, othermetals, or other rigid polymers such as PEEK. At least one advantage ofusing Nitinol for the frame, e.g. braid, is that the frame will bevisible under medical imaging, e.g. fluoroscopy, and will assist a userwith placement of the device. In some embodiments, the braid threads ofexpandable sheath body 202 are radioactive. At least one advantage ofusing superelastic nitinol as a metallic frame is having a frame thatresists kinking and that enables recovery from any mechanicaldeformation the sheath may encounter.

FIGS. 7-9 show illustrative representations of an expandable sheath bodyusing a braid as its frame. FIG. 7 shows an illustrative representationof the expandable sheath body 202 including a braid 700 having a distalend 704 and a proximal end 702, and a lumen extending between theproximal end 702 and the distal end 704. Braid 700 can be made out ofvarious materials and geometry. The braid 700 of FIG. 7 comprises agroup of threads wrapped in a clock-wise spiral direction along thelength 706 and a counter-clock-wise spiral direction along the length708. In some configurations, the groups of threads are wrapped in onespiral direction, clock-wise or counter-clock-wise, along the length.The angle alpha (α) is defined herein as the angle between the axis ofthe braid 714 and the direction 716 of the threads. The angle beta (β)defines the angle between the clock-wise and counter-clock-wise threads.The value of β may be 55 degrees, 45 degrees, 35 degrees, or anothermagnitude (as further described in relation to FIG. 9 below). As shownin FIG. 7 , thread 706 crosses with thread 708 at a corner 710: thread706 can cross on top or below thread 708. The space created betweenthreads, e.g. between thread 706 and thread 708 in FIG. 7 define awindow 712. The window 712 may have a rhombus shape as shown in FIG. 7 .Alternatively, the window 712 may be shaped as a parallelogram, square,or other geometry. In some configurations the braid has a constantpattern down the length of the sheath body 202. In some configurations,there is a variable braid angle along the sheath body 202. In someconfigurations the diameter of the braid is consistent along the sheathbody 202. In some configurations, the braid threads are of the samediameter. In certain implementations, the diameter of the braid materialis between about 1 millimeters and about 10 millimeters. In furtherimplementations, the diameter of the braid material is between about 3millimeters and about 8 millimeters. In some implementations, thediameter of the braid material is between about 5 millimeters and about6 millimeters. In further implementations, the diameter of the braidmaterial is about 5.5 millimeters. In some configurations one or more ofthe threads may be of a different diameter than the rest. In oneconfiguration there is a subset of large threads that are spaced evenlythroughout the braid comprising smaller diameter threads.

A braid configuration is shown in FIG. 8 which shows a braid 800 of theexpandable sheath body 202 with thread pairs 802 a, 802 b, 808 a, 808 b,810 a, and 810 b. Each thread pair (e.g. thread pair 802 a, 802 b)travels “over two” opposing thread pairs (e.g. threads 808 a, 808 b) ata first corner 804, then “under two” opposing thread pairs (e.g. threads810 a, 810 b) at a second corner 806. Accordingly, the constructionshown in FIG. 8 is referred to as a “2 over 2” or “2 strands per threadover two opposing strands” pattern.

FIG. 9 shows an alternative braid configuration which includes a braid900 of the expandable sheath body 202 with threads 902, 908, and 910 ofone strand each. Each thread (e.g. thread 902) travels “over two”opposing threads (e.g. threads 908) starting at corner 904, then “undertwo” opposing threads (e.g. threads 910) starting at corner 906. Theconstruction shown in FIG. 9 is refer to as a “1 over 2” or “1 strandper thread over two opposing threads” pattern. There may be a total of96 strands, 72 strands, 48 strands, or another quantity of strands. Theangle β may be between 5 and 175 degrees. The braid construction can bedefined as 1 over 1, 1 over 2, 1 over 3, 1 over 4, 2 over 2, 2 over 4, 2over 6, or another braid pattern. At least one advantage of a braidpattern of “1 over 1” is that the “1 over 1” is axially stiffer andallows for a larger minimum diameter expandable sheath body 202 comparedto a braid pattern of “1 over 2.” Alternatively, a braid pattern of “1over 2” allows for larger flexibility compared to a braid pattern of “1over 1.”

FIGS. 9 and 10 show illustrative representations of an expandable sheathbody using a laser cut or single wire frame. As mentioned above, insteadof a braid, the frame component of the expandable sheath body may be alaser cut frame (e.g. FIG. 10 ), or a wire-wound frame (e.g. FIGS.11A-C). FIG. 10 shows another alternative expandable sheath bodyconfiguration 1000 with a laser cut frame 1002. The laser cut frame 1002defines a strand which wraps in a spiral direction along the length ofthe expandable sheath body 202. In the embodiment shown in FIG. 10 eachspiral strand (e.g. 1004, 1006) extends along the entire length of theexpandable sheath body 202. Alternatively, the laser cut frame maydefine windows between strands, similar to the braid patterns describedin relation to FIG. 7 and FIG. 9 .

FIGS. 11A-C show another alternative expandable sheath bodyconfiguration with a wire-wound frame 1100. FIG. 11A shows a single wireframe where the wire 1102 is straight between stages 1104 and 1106. FIG.11B shows a single wire frame where the wire 1102 form a helix along thelength of the frame, as visible between stages 1104 and 1106. FIG. 11Cshows an alternative single wire frame where the wire 1102 connectsstages 1108 and 1110, and stages 1108 and 1110 are formed differentlyfrom stages 1104 and 1106 in FIGS. 11A-B. Any of the frame elements forthe expandable sheath body (braid, laser cut or wire-wound) can becombined with one or more coatings. At least one advantage of a singlewire results is having blunted wire crowns or loops (e.g. states 1104and 1106 in FIGS. 11A-B) at the distal end of the frame that loop backand forth. The wire-wound frame provides a high degree of flexibilitywhile controlling the level of foreshortening and “finger-trapping” byadjusting the pattern to have fewer crossover points. The wire-boundframe also increases kink resistance while a winding pattern thatincludes a lower braiding angle or extended longitudinal members wouldreduce risk of buckling during pump removal. A number of winding tooland winding pattern concepts were developed to demonstrate the mostlikely patterns to solve the previously presented design problems. Thetooling models varied by the number of pin arrays and the number of pinsper array. The patterns developed for this application have beendesigned to contribute to a higher column strength to help preventbuckling and allow for an even tension across coating materials duringexpansion.

In one embodiment, the expandable sheath body 202 includes the frame(braid, laser cut or wire-bound), a polymer coating encapsulating theframe, and a hydrophilic coating on an inner surface and/or outersurface of the polymer-coated frame.

FIG. 12 and FIGS. 49-54 show illustrative expandable sheaths withdifferent frame and coating configurations. FIG. 12 shows an example ofa coated frame for an expandable sheath body (e.g. a braid as shown inFIGS. 7-9 ) having a first portion 1204 in a first state (e.g. relaxedstate 404 of FIG. 4B) and a second portion 1202 in a second state (e.g.expanded state 406 of FIG. 4B). A coating 1206, e.g. a polymer coating,fully encapsulates the braid. The polymer coating may be biased to besubstantially along an inner diameter of the frame (e.g. the braid), tocreate a smooth inner surface. Alternatively, the polymer coating may bebiased to be substantially along the outer diameter of the frame (e.g.the braid) to create a smooth outer surface, as discussed in greaterdetail in relation to FIGS. 51 and 52 below. As shown in FIG. 12 , thepolymer encapsulation covers the windows 1208, i.e. the area between thebraid strands. A hydrophilic coating is added over at least a portion ofthe inner surface of the polymer encapsulated frame. Optionally, ahydrophilic coating may also be added over at least a portion of theouter surface of the polymer encapsulated frame. At least one advantageof the frame, the polymer coating and the hydrophilic coatingcombination is to reduce friction during delivery and to avoid clottingby allowing adequate blood flow along the sheath body.

FIG. 49 shows a cross-section of an expandable sheath biased towards theinner diameter of the sheath. The sheath cross-section includes a frame4904 and a coating layer 4902. The frame 4904 in FIG. 49 is a braidedmesh, with wire strands 4905 and 4907. Alternatively, the frame 4904 canbe a laser cut mesh or a single-wire mesh. As shown in FIGS. 49 , frame4904 with strands 4905 and 4907 of the braid material is fullyencapsulated by coating layer 4902, forming a textured outer (i.e.,abluminal) surface 4906 and a smooth inner (i.e., endoluminal) surface4908. The braids of the frame 4904 extend longitudinally along the framebut the coating positions the braids so they protrude away from thelumen of the sheath, so the frame 4904 forms peaks and valleys whichform a corrugated outer surface while the inner surface is smooth, thesheath thus having an inner-diameter bias configuration. A depthdifference 4910 is the difference between a peak and valley. Thiscombination of a low friction surface that can easily expand radiallyfacilitating easy passage of a medical devise, thanks to the sheath. Thetextured outer surface 4906 includes troughs having a depth 4910 betweenadjacent strand pairs 4902 and 4904. At the trough, only the coatinglayer 4902 is present, with a thickness 4912. Advantageously, the smoothinner surface of the sheath in this configuration allows a medicaldevice to be inserted through the sheath, and the coating layer 4902with a relatively small thickness 4912 at the trough does not preventframe 4904 from expanding, e.g. wire strands 4905 and 4907 remain freeto move relative to one another. The depth difference 4910 is selectedto reduce the risk of clot formation on the sheath. For example, therisk of clot formation on the sheath is reduced if the depth difference4910 is less than around 100 μm. In yet another example, the risk ofclot formation on the sheath is significantly reduced if the depthdifference 4910 is less than around 60 μm.

FIG. 50 shows a cross-section of an expandable sheath in an alternativeconfiguration with no bias. The cross-section includes a frame 5004 anda coating layer 5002. The frame 5004 in FIG. 50 is a braided mesh, withwire strands 5005 and 5007. Alternatively, the frame 5004 can be a lasercut mesh or a single-wire mesh. As shown in FIG. 50 , the frame 5004 isfully surrounded (also referred to as encapsulated) by the coating layer5002, forming both a smooth outer surface and a smooth inner surface. Inthis configuration, a thickness of the coating layer 5002 is effectivelyconstant throughout the sheath and equal to or greater than a thicknessof the frame 5004. For example, the thickness of the coating layer 5002is twice the thickness of one strand of the braid material. As shown inFIG. 50 , both the inner surface 5008 and the outer surface 5006 of thesheath are smooth. At least one advantage of this configuration withrespect to the configuration shown in FIG. 49 is the ability to preventblood collection and clotting on the sheath. The thickness of thecoating layer 5002, and the coating layer 5002 fully encapsulating theframe 5004 may require a larger force to be applied to expand thesheath. For example, the coating layer 5002 may limit the sheath wirestrands 5005 and 5007 in their relative motion and their ability toexpand or contract.

FIG. 51 shows a cross-section of an expandable sheath biased towards theouter diameter of the sheath. The sheath cross-section includes a frame5104 and a coating layer 5102. The frame 5104 in FIG. 51 is a braidedmesh, with wire strands 5105 and 5107. Alternatively, the frame 5104 canbe a laser cut mesh or a single-wire mesh. As shown in FIG. 51 , thecoating layer 5102 creates a smooth outer surface 5106, similar to theouter surface 5006 of the sheath of FIG. 50 , advantageously minimizingclotting on the outside of the sheath. The braids of the frame extendlongitudinal along the frame but the coating positions the braids sothey protrude into the lumen of the sheath. The interior coating is thinand creates a thin surface around the interior face of the braids. Thethin coating extends around the braids forming peaks and valleys/troughsalong the interior lumen of the sheath. The peaks correspond to theheight of the overlapping strands of the braid, whereas thevalleys/troughs correspond to the space between the overlapping strandsof the braid. A depth difference 5110 is the difference between a peakand valley. The textured inner surface 5106 includes valleys/troughshaving a depth 5110 between two adjacent strand pairs 5105 and 5107. Atthe trough, only the coating layer 5102 is present, with a thickness5112. Because the interior peaks are covered with the thin film, theyare low in friction, and have limited constraints for moving relative toeach other, facilitating easy radial expansion. This combination of alow friction surface that can easily expand radially facilitates easypassage of a medical device through the sheath. Advantageously, theinner surface of the sheath in this configuration allows a medicaldevice to be inserted through the sheath while contacting only the peaksof the sheath on the sheath inner diameter. Advantageously, a deviceinserted through the sheath is in contact with a smaller surface area ofthe sheath than the configurations of FIGS. 49 and 50 . As shown in FIG.51 , the coating layer 5102 advantageously provides both a smooth outersurface, and a reduced surface area on the inner surface of the sheath.

FIG. 52 shows a cross-section of an alternative expandable sheath (e.g.expandable introducer sheath 200 of FIG. 2 ) having an outer-diameterbiased arrangement. The sheath cross-section includes a frame 5204, anouter coating layer 5206, and an inner coating layer 5202. The outercoating layer 5206 is an elastomer or similar material. For example, theouter coating layer 5206 may be a polymer. In some implementations, thepolymer layer comprises at least one of polyether, and polyurethane. Incertain implementations, the polyurethane comprises TPU. In someimplementations, the TPU has a durometer between about D20 and aboutD90. In certain implementations, the TPU has a durometer between aboutD30 and about D80. In further implementations, the TPU has a durometerbetween about D40 and about D70. In some implementations, the TPU has adurometer between about D50 and about D60. In further implementations,the TPU has a durometer of about D55. The frame 5204 in FIG. 52 is amesh, for example, a braided mesh, with wire strands 5205 and 5207.Alternatively, the frame 5204 can be a laser cut mesh or a single-wiremesh. As shown in FIG. 52 , the outer coating layer 5206 covers an outersurface of the frame 5204. Advantageously, the outer coating layer 5206defines a smooth outer surface of the expandable sheath, and covers theopen spaces (also referred to as “windows”) created by frame 5204. Thesmooth outer surface of outer coating layer 5206 further reduces therisk of trauma to the vessel when the sheath is inserted, and reducesthe risk of blood clots forming on the surface of the expandable sheath.

As shown in FIG. 52 , the inner surface of the expandable sheath iscoated with a coating 5202. This coating 5202 extends over an innersurface of the outer coating 5206, as well as over the perimeter of theframe 5204 not already covered by coating 5206. The coating 5202 is thinand is applied tightly about the mesh interior surface so as to sharethe contoured shape of the mesh strands on the outer side. The innercoating 5202 extends around the braids forming peaks and valleys/troughsalong the interior lumen of the sheath. The peaks correspond to theheight of the overlapping strands 5205 and 5207, whereas thevalleys/troughs correspond to the space between the overlapping strands5205 and 5207. The coating 5202 can be silicone and/or a hydrophobic orhydrophilic material, or any other coating that is suitable to provide alow friction surface for passage of a medical device through the lumen.The coating is thin so the sheath can readily expand to facilitatepassing of the medical devise while the low friction outer surfacefacilitates sliding of the device. A thickness of the coating 5202 is onthe order of a few microns. For example a thickness of the coating 5202is about 5-20 microns. As shown in FIG. 52 , the textured inner surfaceof the sheath advantageously minimizes a surface area in contact withdevices inserted through the sheath. Furthermore, as shown in FIG. 52 ,a thickness 5209 of the outer coating layer 5206 is less than athickness of the frame 5204, and less than a thickness of one wirestrand 5205 or 5207. For example, a thickness 5209 of the outer coatinglayer 5206 is on the order of about 80-100 microns.

The coating is thin so the sheath can readily expand to facilitatepassage of the medical device, while the low friction outer surfacefacilitates sliding passage of the device. As shown in FIG. 52 , theouter coating layer 5206 contacts and covers an outer portion of thewire strands 5205 and 5207, but does not fully encapsulate the wirestrands, and does not encapsulate the interface 5211 between wire strand5205 and 5207. FIGS. 55 and 56 , described in further detail below showthis configuration, with coating layer 5506 (or 5606) being in contactwith some but not all of the frame elements 5504 (or 5604) reduces thethickness. The coating layer 5206 may be in contact with only a portionof the frame 5204. For example, the coating layer 5206 may be in contactwith less than about 50% of the outer surface of frame 5204. In anotherexample, the coating layer 5206 may be in contact with less than about25% of the outer surface of frame 5204. In yet another example, thecoating layer 5206 may be in contact with less than about 10% of theouter surface of frame 5204. The configuration of the outer coatinglayer 5206 as shown in FIG. 52 (contacting but not fully encapsulatingthe frame) is advantageous in preserving the ability of the frame (e.g.wire strands 706 and 708, as described in relation to FIG. 7 ) to expandand contract such that the expandable sheath (e.g. expandable sheath 200in FIG. 2 ) can expand and contract as desired. The outer coating layeris a silicone and/or hydrophobic or hydrophilic coating. As described inrelation to FIGS. 57 and 58 for manufacturing of an expandable sheath,the sheath may be formed by various processes. For example, the coating5206 may be a separate layer heat bonded to the frame 5204 (e.g. asdescribed further in relation to FIG. 57 ), or may be formed using anouter-diameter biased dipping process with a solvent-polymer coatingsolution (e.g. as described further in relation to FIG. 58 ). In someconfigurations, a separate hydrophobic coating may be applied to theouter surface and/or inner surface of the sheath.

FIGS. 53 and 54 show example prototypes of an expandable sheath (e.g.expandable sheath 200 of FIG. 2 ) after use. FIG. 53 shows a prototypeof an expandable sheath 5300 representative of a used sheath with asmooth outer surface (e.g. configured according to FIG. 50, 51 , or 52)or a sheath with an inner diameter biased geometry (e.g. configuredaccording to FIG. 49 ) with a depth difference 4910 selected to minimizeclotting but maximize flexibility. As shown in FIG. 53 , the sheath 5300has been used (e.g. either placed in a patient or subjected tothrombogenicity testing in a laboratory setting), FIG. 53 shows aprototype with a smooth outer surface, having negligible thrombus growthand adhesion on the outer surface of the sheath 5300. In contrast, FIG.54 shows an exemplary prototype of an expandable sheath 5400representative of a used sheath either without a coating layer (e.g. anopen cell wire mesh sheath) or a sheath with an inner diameter biasedgeometry with an inadequate depth difference 5110. The sheath of FIG. 54has significant build-up on its surface. It also has an expandablesheath with a trough depths greater than a thickness of the framestrand, e.g. greater than 100 μm. As shown in FIG. 54 , the sheath shown5400 has been used (e.g. either placed in a patient or subjected tothrombogenicity testing in a laboratory setting), FIG. 54 showssignificant thrombus growth and adhesion on sheath 5400 due to thelarger trough depth.

As discussed earlier in relation to FIG. 12 , a coated frame for anexpandable sheath body (e.g. a braid as shown in FIGS. 7-9 ) can havedifferent portions of the sheath body in different states. The differentstates can be achieved or accommodated by varying the properties and/orpositioning of the sheath frame (e.g. by varying the relative positionof threads forming a braid frame). For example, as shown in FIG. 12 afirst portion 1204 in a first state (e.g. relaxed state 404 of FIG. 4B)and a second portion 1202 in a second state (e.g. expanded state 406 ofFIG. 4B). A relaxed state (e.g. relaxed state 404 of FIG. 4B) is definedas a state the expandable introducer sheath is in when no externalforces are applied to the expandable introducer sheath, e.g. no tensileforces, and or no radially expanding or compressing forces. An expandedstate (e.g. expanded state 406 of FIG. 4B) is defined as one in whichradially outward forces may be applied to the expandable introducersheath, such that its diameter increases. In the embodiment of FIG. 12 ,the diameter of the second portion of the sheath 1202 is larger than thediameter of the first portion of the sheath 1204. Accordingly, the betaangle—the angle between the threads, discussed above in relation to FIG.7 , is larger for the second portion 1202 than the beta angle of thefirst portion 1204. The strain in the coating 1206 across each window1208 is higher in the expanded state than the relaxed state 1204. Theexpansion from a relaxed state 1204 to the expanded state 1202 throughan increase in diameter also causes a length shortening caused by theincrease in beta angle. As the diameter expands, the braid threads shiftcausing an increase in the beta angle, the angle between the threads, aspreviously described in relation to FIG. 7 . The beta angle is selectedto both reduce the force of insertion required to insert device (with alow beta angle the braid contributes less radial resistance to expansionas a medical device is passed through) and to ensure that a braidreduction in length as the device is passed through does not reduce thebraid length to be less than a length of the device itself. A braid withthe described structure and functionality defines one concept of theexpandable sheath body 202.

The frame material and coating material are selected to allow for thinframe walls while maintaining axial stiffness and elasticity. Thecoating may be made of a material such as a polymer. The polymer coatingcan be silicone or thermoplastic polyurethane. In some instances, thepolymer fully covers the entire length of the frame and the sheath bodyexhibits a homogenous construction (frame and coating) along the entirelength of the sheath. In other instances, the coating extends over aproximal portion of the braid, covering between 5 and 50% in length ofthe proximal portion of the braid. Alternatively, the coating extendsover a distal portion of the frame, covering between 5 and 50% in lengthof the distal portion of the braid. In other instances, the coatingextends over any portion of the frame, and covers between 5 and 95% ofthe length of the frame. In other instances, the coating extends overmultiple portions of the frame, and the portions can be discontinuous inlength, and/or discontinuous in circumference. The polymer encapsulationshould be of a low elastic modulus as exhibited by typical Shore ASilicones and Shore A and Shore D thermoplastic polyurethanes. Thematerial for coating the frame can be varied specific to the performancerequirements of the expandable sheath body 202. A material with a lowerelastic modulus allows for lower radial strength to promote expansionwhile a material with a higher elastic modulus allows for strongerdurability to prevent coating failure during use. Elastomers that areurethane based may allow for additional hydrophilic coatings on theinner and outer layer to reduce frictional forces experienced by theopening and inner surface of the blood vessel. Thicker elastomercoatings are beneficial for the durability of the coating and increasethe stiffness of the expandable sheath body 202. Thinner elastomercoatings promote radial expansion and allows for delivery of the heartpump through smaller sheath profiles. Materials are further selected tobe biocompatible such that they can be in direct and continuous contactwith blood within the circulatory system for up to 28 days. Any of thematerials described above can be used in any expandable sheath frameconfiguration, including for example any of the configurations discussedabove in relation to FIGS. 51 and 52 .

At least one advantage of a metallic and polymer/elastomer compositeconstruction for the frame and coating of the sheath body is the abilityto have a thin-walled construction≤200 microns (0.008″), minimizingarteriotomy size, improving vessel closure, and minimizing vascularcomplications (i.e. bleeding/oozing). In contrast, conventional polymersheaths capable of passing a 14 Fr device have wall thicknesses around˜400 micron and conventional sheaths capable of passing a 23 Fr devicehave wall thicknesses around ˜680 micron. At least another advantage ofthe metallic and polymer/elastomer composite construction from the frameand coating is the ability to retain axial stiffness (for pushabilityand buckling resistance) while maintaining bending flexibility and kinkresistance that would not be possible with a thin-walled construction ofeither a polymer/elastomer sheath or a metallic sheath.

FIGS. 57 and 58 outline examples of different processes 5700 and 5800for coating a sheath body 202 (e.g. expandable sheath 202 of FIG. 2 ) toprovide an outer-diameter biased expandable sheath (e.g. as shown inFIG. 52 ). For example, processes 5700 or 5800 can be carried outinstead of or in combination with process 1500 described in relation toFIGS. 13-15 below.

FIG. 57 shows a process 5700 of encapsulating and coating an expandablesheath (e.g. sheath 202 of FIG. 2 ) using thermal bonding. At step 5702,a sheath frame is primed for adhesion to a polymer layer. For example,the sheath frame is primed for adhesion using a priming solution. Thepriming solution can be a low bodied TPU solvent with the TPU beingLubrizol Tecoflex SG-80A and the solvent being THF. The priming can bedone with Kommerling Cilbond 49SF. The polymer layer to which the sheathframe is to be adhered is formed separately. For example, the polymerlayer can be extruded, or dip cast. The polymer layer can be TecoflexEG-80A or SG-80A. The polymer layer can have an inner diameter betweenaround 1 mm and 8 mm. For example, the polymer layer can have an innerdiameter between around 3 Fr and 27 Fr. The wall thickness of thepolymer layer can be between 20 μm and 150 μm.

At step 5704, a tip layer is assembled over the sheath frame. The tiplayer may be slid over the distal end of the sheath frame. At step 5706,the tip layer is bonded to the sheath frame. The tip layer and thesheath frame are bonded by heating at a specified temperature over aspecified time duration.

At step 5708, the polymer layer is assembled over the sheath frame. Thepolymer layer may be slid over the sheath frame. Alternatively, apolymer sheet may be wrapped around the sheath frame and sealed into alayer.

At step 5710, the polymer layer and the sheath frame are bonded byheating at a specified temperature over a specified time duration.Advantageously, the specified temperature and specified duration areselected to adequately fuse the sheath frame and polymer layer butreduce or avoid overpenetration of the polymer layer and the sheathframe. In some configurations, the specified temperature and specifiedtime duration may comprise a range of temperatures and a range of timedurations, applied in sequence. For example, the specified temperaturemay range between 300 F and 500 F. For example, the specified timeduration may range between 5 seconds to 5 minutes. Heating may takeplace in an oven, with heated air being fed from a hot air nozzle ontothe sheath frame and polymer layer assembly. For example, hot air fromthe hot air nozzle may be dispensed at 0.1 mm/min to 1 mm/min.Similarly, at step 5712, the tip layer and the polymer layer are bondedby heating at a specified temperature over a specified time duration.

After the polymer layer and the sheath frame are bonded to one another,at step 5714, an inner surface of the expandable sheath (e.g. the innersurface as shown in FIG. 52 ) is coated with a lubricious material.Alternatively or additionally, a hydrophilic or hydrophobic siliconelayer may be further applied on the inner surface of the expandablesheath. The hydrophilic material may be applied to the inner surface ofthe expandable sheath in combination with a solvent, and the solventevaporated. Alternatively or additionally, at least a portion of theouter surface of the expandable sheath (e.g. the outer surface as shownin FIG. 52 ) is coated with a hydrophilic material.

FIG. 58 shows an alternate process 5800 of encapsulating and coating anexpandable sheath (e.g. sheath 202 of FIG. 2 ) by using anouter-diameter biased dipping process. At step 5802, a polymer solventsolution is created. The polymer can be silicone, specifically NusilMED10-6600 or MED10-6400. The solvent can be xylene. At step 5804, atube is dipped into the polymer solvent solution. The inner diameter ofthe tube can be equal to the desired outer diameter of the finishedexpandable sheath. At step 5806, a sheath frame is inserted into thetube to encapsulate the sheath frame with the polymer solvent solutionpresent on the inner diameter of the tube. At step 5807 an additionalamount of polymer solvent solution is inserted into the sheath frame, tocoat the inner surface of the sheath frame. At step 5808, the sheathframe is removed from the tube. Similar to step 5714 described above, atstep 5810, a hydrophilic or hydrophobic coating is applied. Thecharacteristics of the polymer solvent solution can be used to controlthe thickness of the outer-diameter biased polymer layer on the sheathframe. For example, the viscosity of the polymer solvent solution can beused to control the thickness of the applied polymer, with highviscosity yielding thicker solution. Additionally, the speed of theremoval of the solvent can be used to control the thickness of theouter-diameter biased polymer layer. For example, slower removal createsa thinner polymer layer. At both steps 5804 and 5807, the polymersolvent solution can be introduced by dipping or by injecting thesolution. Using Silicone as the polymer in the polymer solvent solutionis advantageous because Silicone is a thermoset which allows forcross-linking between the polymer chains and the frame, making it easierto use during bonding and other manufacturing steps.

Processes 5700 and 5800 may be used to manufacture all of the expandablesheath, or a portion of the expandable sheath. For example, a sheathbody may be formed using either process 5700 or 5800. A sheath tip maybe formed using a different process. The sheath tip may be formedintegrally with the sheath body. Alternatively, the sheath tip may beformed separately from the sheath body, and later attached to the sheathbody, e.g. via bonding.

FIGS. 55 and 56 show cross-sections of exemplary prototypes of anexpandable sheath on a mandrel. FIG. 55 shows a cross section where thethickness of the coating is equal or greater to twice the wire diameter.As shown in FIG. 55 the inner surface of the expandable sheath 5500 issmooth—there are no peaks or valleys. The sheath shown in FIG. 55 can bemanufactured by traditional dipping, or by laminating. Traditionaldipping results in the inner diameter biased configuration (e.g. asshown in FIG. 49 ). In some examples, when laminating a heat shrink tubemay be used. FIG. 56 shows a cross section with an outer diameter biasedcoating (e.g. as described in relation to FIG. 52 ). As shown in FIG. 56, the inner surface of the expandable sheath 5600 is smooth—there are nopeaks or valleys. In addition, as shown in FIG. 56 , the relatively thincoating layer 5602 does not fully encapsulate the sheath frame 5602. Thesheath shown in FIG. 56 can be manufactured using a dipping techniquesuch as the outer-diameter dipping technique described in relation toFIG. 58 , or by using a thermal bonding technique such as the thermalbonding technique described in relation to FIG. 57 .

FIGS. 13 and 14 illustrate isometric views of braid tip manufacturingstages. FIG. 13A illustrates a mandrel 1302 having a design machinedonto the tip 1304. A braid 1306 can then be loaded onto the mandrel 1302such that the distal tip of the braid 1306 is adjacent to the tip of themandrel 1304. FIG. 13B illustrates the stage before the mandrel 1302 islowered into a dip container 1308 containing silicone 1310. FIG. 14Aillustrates the stage when the tip of the mandrel 1304 is lowered intothe dip container 1308. FIG. 14B illustrates the stage when the tip ofthe mandrel 1304 is removed from the dip container 1308. After the braid1306 is unloaded from the mandrel 1302, the design machined onto the tip1304 is transferred to the distal tip of the braid 1306.

FIG. 15 shows a process 1500 of encapsulating and coating a sheath body202, described above in relation to FIGS. 8, 9, and 12 . At step 1502, asheath body 202 is dipped into a polymer container. At step 1504, thebraid of the sheath body 202 is encapsulated with the polymer. At step1506, the polymer encapsulating the braid of the sheath body 202 isexposed to a hydrophilic coating. At step 1508, the polymerencapsulating the braid of the sheath body 202 is coated with thehydrophilic coating, and a chemical reaction between the polymer andhydrophilic coating results in bonding between both. The result ofprocess 1500 is shown illustrated in FIGS. 16-18 and 49-52 .

FIG. 16 shows an isometric view of a sheath body 202 having a braid1602, encapsulated by a polymer 1604, which in turn is coated with ahydrophilic coating 1606. FIGS. 17 and 18 show cross-sectional views ofthe braid 1602 (e.g. with overlapping threads 1602 a and 1602 b)encapsulated by the polymer 1604. The distance between the peak of thebraid 1602 and the trough of the polymer 1604 in the windows of thebraid may range between 0 μm, when the polymer thickness is twice thethread diameter and 200 μm, when the thread diameter is 100 μm and twothreads are stacked, assuming a near-zero polymer thickness. Asdiscussed in relation to FIG. 12 , the polymer encapsulates the frame ofthe expandable introducer sheath 202, including the threads but alsoforming a layer over the windows. As shown in FIG. 18 , one surface ofthe polymer encapsulation is flat. In one embodiment and as furtherdescribed in relation to FIG. 49 below, the inner surface the sheathbody has a smooth surface and the outer surface of the sheath body hastroughs 1604. In another embodiment and as further described in relationto FIGS. 50 and 51 below, the outer surface of the sheath body can besmooth to prevent blood collection and clotting thereon and reducehemolysis. This configuration can also provide a minimal thickness ofthe sheath body which is desirable to minimize the size of the openingin the vessel through which the sheath body must pass through. Inanother embodiment and as further described in relation to FIG. 51below, the inner surface of the sheath body has troughs 1604 and theouter surface of the sheath body has a smooth surface.

Introducer sheath 200, dilator assembly 2000, and hemostasis styletassembly 4600 can be used in combination to form a sheath assembly forthe insertion of a medical device into a blood vessel. In someimplementations, the sheath assembly includes an introducer sheath 200and a dilator assembly 2000. This configuration allows for the insertionof the introducer sheath 200 into an opening of the blood vessel and theexpansion of the opening using the dilator assembly 2000. In otherimplementations, the sheath assembly 100 includes an introducer sheath200 and a hemostasis stylet assembly 4600. This configuration allows forthe regulation of hemostasis between the opening of the blood vessel andthe introducer sheath 200. In certain implementations, the sheathassembly 100 includes an introducer sheath 200, a dilator assembly 2000,and a hemostasis stylet assembly 4600.

FIGS. 59 and 60 show isometric views of the expandable sheath system ofFIG. 21 , including an illustrative delivery system and illustrativesheath hub. FIGS. 61 and 62 show isometric views of the illustrativesheath hub of FIGS. 59 and 60 . In one embodiment, sheath hub 6200includes a sidearm port 6202 which provides connection to a sidearm (notshown). FIG. 63 shows a cross-section of an illustrative sheath hub 6300including a strain relief 6302, an expandable sheath 6304, a compressioncap 6306, a hub 6308, a hemostasis valve 6310, and a retainer cap 6312.

FIG. 19 shows a process 1900 of inserting a pump into a blood vesselusing an introducer sheath 200, a dilator assembly 2000, and ahemostasis stylet assembly 4600, described above in relation to FIGS. 2,20, and 46 , respectively. At step 1902, an introducer sheath 200 isattached to a dilator assembly 2000. The introducer sheath 200 caninclude an expandable sheath body 202 having a first diameter D1 and afirst length L1. FIG. 29 (described above) illustrates the introducersheath 200 and dilator assembly 2000 with the sheath 200 attached to thedilator assembly 2000.

At step 1904, the dilator assembly 2000 moves in the proximal directionwith respect to the introducer sheath 200 such that the expandablesheath body 202 of the introducer sheath 200 contracts to a seconddiameter D2 and a second length L2. The second diameter D2 is smallerthan the first diameter D1 and the second length L2 is greater than thefirst length L1.

At step 1906, the introducer sheath 200 and the dilator assembly 2000are inserted into a desired location in a blood vessel. The opening ofthe blood vessel expands to accommodate the second diameter D2 of theexpandable sheath body 202.

At step 1908, the dilator assembly 2000 moves with respect to theintroducer sheath 200 in the distal direction. The expandable sheathbody 202 of the introducer sheath 200 expands to a third diameter D3 anda third length L3. The third diameter D3 is greater than the seconddiameter D2 and the third length L3 is smaller than the second lengthL2. The opening of the blood vessel expands to accommodate the thirddiameter of the expandable sheath body 202.

At step 1910, the dilator assembly 2000 is detached from the introducersheath 200 and removed from the desired location in the blood vessel.FIG. 25 (described below) shows the dilator assembly 2000 being removedfrom the introducer sheath 200.

At step 1912, a pump is inserted through the introducer sheath 200. Theexpandable sheath body 202 expands to a fourth diameter D4 toaccommodate the pump as the pump traverses within the introducer sheath200. The fourth diameter D4 is greater than the third diameter D3. Theopening of the blood vessel expands to accommodate the fourth diameterD4 of the expandable sheath body 202. FIG. 5 (further described above)shows the insertion of a pump 502 through the introducer sheath 200.

At step 1914, a hemostasis stylet assembly 4600 is inserted through theintroducer sheath 200. The expandable sheath body 202 expands to a fifthdiameter D5 to accommodate the hemostasis stylet assembly 4600 as thehemostasis stylet assembly 4600 traverses within the introducer assembly200. The fifth diameter D5 is such as to achieve hemostasis between theopening of the blood vessel and the expandable sheath body 202.

As discussed above in relation to steps 1902-1910 of FIG. 19 , a dilatorassembly is used in combination introducer sheath 200 and hemostasisstylet 4600 to form a sheath assembly for the insertion of a medicaldevice into a blood vessel. FIGS. 20-25C show various components of thedilator assembly and their relative motions while carrying out steps1902-1910 as discussed in relation to FIG. 19 .

FIG. 20 shows a dilator assembly 2000 with an outer dilator 2002, innerdilator 2004, hub attachment 2008, and tip interlock 2018. The distalend of the inner dilator 2004 consists of a tube with a distal end, aproximal end, and a lumen defined through. It is bonded to a tip 2006,with the proximal end of the inner dilator 2004 bonded to a luer hub2020. The outer dilator 2002 is axially aligned with the inner dilator2004 and has a length less than the inner dilator 2004 such that theinner dilator 2004 is exposed on either end and slides within the outerdilator 2002. The hub attachment 2008 consists of a hub attachment cap2010 that contains features to attach to the hub 204 of a sheath on thedistal end and is bonded to a luer assembly 2014 containing acompressible elastomer 2012 and a compression nut 2016. When thecompression nut 2016 is loose the compressible elastomer 2012 is in afirst state of minimum compression allowing the hub attachment 2008 toslide along the outer dilator 2002. When the compression nut 2016 istightened the compressible elastomer 2012 is in a second state ofmaximum compression preventing the hub attachment 2008 from sliding onthe outer dilator 2002 and locking the hub attachment 2008 in place withrespect to the outer dilator 2002. FIG. 21 shows illustrative example ofan introducer sheath assembly 2100 comprising an expandable introducersheath 200 (as described in FIG. 2 ) and dilator assembly 2000 (asdescribed in FIG. 20 ), with a distal tip 2006 and a sheath handlemechanism 2008.

At least one advantage of the integration of the introducer sheath 200and the dilator assembly 2000 is that the integration allows forexpansion of the opening of the blood vessel while using the sameintroducer sheath 200 for insertion of a pump. This removes thenecessity of the peel away introducer and sheath exchanges, reducing therisk of migration and bleeding. In addition, an additional sheath doesnot need to be advanced into the blood vessel for pump insertion,reducing the risk of further damage to the blood vessel. Finally,guidewire access is maintained throughout the procedure allowing thepump to be removed with the introducer sheath 200 in place.

FIGS. 64-69 show cross sections of a sheath and dilator systemconfigured for insertion into a body lumen, and changes in relativepositions of the sheath and dilators between insertion on one hand, andwhen the sheath is relaxed at a desired location and both dilators arewithdrawn on the other hand. FIG. 64 shows detail regarding relativepositions of the sheath and dilators when configured for insertion, e.g.as shown in FIG. 65 .

The dilator system of FIGS. 64-69 is configured so the dilators can beused to position the sheath by assembling the sheath and the dilatorsand then inserting the assembly into the patient. FIG. 64 shows across-section of a mechanism by which the combination of inner dilator6410 and outer dilator 6408 retains or entraps the distal tip 6402 ofthe expandable sheath. As shown in FIG. 64 , the combination of innerdilator 6410 with its inner dilator tip 6405 and outer dilator 6408entraps a distal tip 6402 of an expandable sheath (e.g. sheath 202 ofFIG. 2 ). The inner dilator 6410 has a shaft with an inner lumen 6411extending along the shaft. The inner dilator 6410 is connected at itsdistal end to an inner dilator tip 6405. The inner dilator tip 6405 hasa shape including inner dilator tip wings 6406 which extend proximallyof a distal end of the inner dilator. For example, the inner dilator tipwings 6406 have a greater diameter than the diameter of the shaft of theinner dilator 6410. For example, the inner dilator tip 6405 is the shapeof a cone, or an arrow-head. The inner dilator has an interior lumen6411 which extends through the length of the inner dilator shaft andthrough to the end of the inner dilator tip 6405, to allow passage of aguidewire.

The outer dilator 6408 has an inner lumen 6409 which extends throughoutthe outer dilator 6408. The outer dilator and the inner dilator arecoaxial, one over the other. As shown in FIG. 64 , the inner dilatorlies within the outer dilator inner lumen 6409. The outer dilator 6408has a proximal portion and a distal portion, separated by a transitionportion 6413, which transitions from the outer dilator proximal portiondiameter to the outer dilator distal portion diameter. For example, theouter dilator proximal portion has a diameter which is greater than adiameter of the distal portion of the outer dilator. The transitionportion 6413 may be in the shape of a frustum, a cone, a concave orconvex shape. The transition portion 6413 on the outer dilatorcorresponds to a surface 6407 at the proximal end of the inner dilatortip wings 6406. For example, the surface 6407 may be in the shape of afrustum, a cone, a concave or convex shape. The outer dilator distal tipterminates with a surface 6419. In one example, end surface 6419 issubstantially radial. In another example, end surface 6419 has a partialradial component. The shaft of inner dilator 6410 is attached to theinner dilator tip 6405 at connection element 6412. For example the shaftand the inner dilator tip may be bonded together, or may be moldedtogether, or affixed by a connector.

To obtain the assembly shown in FIG. 64 , the sheath is inserted intothe dilator tip, and then the inner dilator tip, inner dilator 6410, andthe sheath subassembly is retracted back until the outer dilator 6408 isin place within the sheath and the inner dilator tip, trapping the tipof the sheath. This is the configuration shown in FIGS. 64 and 65 . Ifthe sheath is being introduced into the vasculature in a relaxed state,the sheath inner dilator and sheath is retracted until the sheath hublocks into the delivery system hub. If the sheath is being introducedinto the vasculature in a compressed state, the user draws back thesheath hub into the delivery system hub, drawing the diameter of thesheath down to the prescribed amount. This allows for the sheath tip tobe delivered to the customer assembled and the sheath has no stress ofassembly. The materials of the sheath are sensitive to stress,viscoelastic, and subject to high creep, and therefore would likely havesignificant permanent deformation after sterilization or shelf life.

As shown in FIG. 64 , when the inner dilator shaft is placed within theinner lumen 6409 of the outer dilator 6408, and the transition surface6413 of the outer dilator is pushed as far as possible distally, thereis a free space 6403 between the distal end of the outer dilator 6408and the portion of the inner dilator 6410 between the outer surface ofthe shaft of the inner dilator 6410 and the inner surface of the innerdilator tip wings 6406. Additionally, as shown in FIG. 64 , and indetail A of FIG. 64 , there is an annular gap 6417 between the outersurface of outer dilator 6408 and the inner surface of the inner dilatortip wings 6406. As shown in FIG. 64 , the sheath body 6404 has athickness 6420 which is less than the height of annular gap 6417.Accordingly, absent any forces, the sheath body 6404 can move in adistal direction within the annular gap 6417, and can move radiallywithin annular gap 6417. However, as also shown in detail A of FIG. 64 ,the distal tip 6402 of the sheath has a thickness 6416 which is greaterthan the height of the annular gap 6417, such that the sheath distal tip6402 cannot be pulled in a proximal direction into the annular gap 6417.As shown in detail A of FIG. 64 , when the sheath is pulled in aproximal direction, e.g. when the sheath is in a stretched or tensionedconfiguration (e.g. configuration 6500 as shown in FIG. 65 , forinsertion into a body lumen), the sheath distal tip 6402 abuts the endsurface 6419 of outer dilator 6408. The sheath distal tip 6402 isentrapped in the free space 6403—the sheath distal tip can move in adistal direction, but is prevented from moving in a proximal directionpast the end surface 6419 of outer dilator 6408. The sheath distal tip6402 is released from the entrapped configuration shown in FIG. 64 bymoving the inner dilator 6410 and the outer dilator 6408 relative toeach other in a longitudinal direction, as shown and described inrelation to FIGS. 65-69 . The sheath distal tip 6402 may additionallyhave a taper, as shown in FIG. 64 . Alternatively the sheath distal tip6402 may have a constant diameter.

Because the thickness 6416 of the sheath distal tip 6402 is greater thanthe thickness 6420 of the sheath body, the sheath distal tip 6402 isstiffer than the sheath body 6404. Alternatively, even in configurationswhere the sheath distal tip 6402 does not have an increased thickness6416 relative to a thickness of the sheath body, the sheath distal tipmay be made stiffer than the sheath body by increasing the volume ratioof frame to coating, or by selecting materials with a higher stiffness.For the entrapment configuration shown in FIG. 64 , the thickness 6416of the sheath distal tip 6402 may be obtained by varying the thicknessof at least one of the sheath frame, the sheath polymeric cover layer,and/or the additional coating (e.g. hydrophobic and/or siliconecoating). Alternatively, the sheath distal tip 6402 may be formedwithout a frame element, of at least one of the polymeric cover elementand/or the additional coating (e.g. hydrophobic and/or siliconecoating). Alternatively, materials used for the sheath distal tip 6402may be different from the materials used for the sheath body (e.g.described in FIGS. 22-25 ).

In the configuration shown in FIG. 64 , although the sheath is stretchedand in tension, the abutment between the sheath distal tip 6402 havingan increased thickness 6416 and the end surface 6419 of the outerdilator is what prevents the sheath from sliding toward a proximaldirection. Although a portion of the sheath body is present between thetransition 6413 on the outer surface of the outer dilator 6408 and thecorresponding geometry 6407 at the proximal end of the inner dilatorwings 6406, there is no pinching or gripping of the sheath between 6407and 6413.

FIG. 65 shows a cross-section of an initial configuration 6500 forinsertion of a sheath and dilator assembly into a body lumen. Thedilator assembly includes inner dilator 6510 and outer dilator 6508.Outer dilator 6508 is coaxial with and located around inner dilator6510. The outer dilator is configured to fit within the distal region ofthe sheath 6504, so the sheath is located over the outer dilator 6508.Outer dilator 6508 has an interior lumen 6509 through which the innerdilator 6510 passes. Inner dilator 6510 has an interior lumen 6511extending through both the shaft and the distal tip 6505 of the innerdilator, and which can accommodate a guidewire for insertion of thedilator and sheath assembly. At a proximal end of the dilator and sheathassembly (not shown in FIG. 65 ), a proximal end of the sheath issecured in place at a hub (e.g. hub 204 of FIG. 2 ). Movement of thesheath distal tip in a longitudinal direction is prevented by the innerdilator 6510 and outer dilator 6508 combination, and the sheath isstretched over the dilators 6508 and 6510 toward a proximal direction.As a result, the sheath shown in FIG. 65 is stretched and in tension. Asshown in FIG. 64 , the sheath distal tip 6402 is entrapped in the freespace 6403 defined by an inner diameter of the inner dilator tip wings6406, an outer diameter of the inner dilator shaft, and a distal end ofthe outer dilator 6408. An entrapment mechanism by which the combinationof inner dilator 6510 and outer dilator 6508 retain or entrap the sheathdistal tip 6402 is shown and described in greater detail in relation toFIG. 64 . The inner dilator 6510 includes a distal tip proximallyextending flange that optimally mates with the distal portion of theouter dilator 6508. Prior to the loaded configuration shown in FIG. 65 ,the sheath, inner dilator and outer dilator are assembled outside of thepatient body. This assembly prior to the loaded configuration shown inFIG. 65 is also discussed in greater detail in relation to FIG. 64 .

Returning to FIGS. 65-69 , to release the sheath from its stretched andtensioned configuration as shown in FIGS. 64 and 65 , the inner dilatorand outer dilator are moved relative to each other, as shown in FIG. 66. FIG. 66 shows the configuration 6600 of the sheath system tip in asecond position. In configuration 6600, the inner dilator 6610 is pushedtoward a distal direction independently of the outer dilator 6608,resulting in a longitudinal gap between the inner dilator tip wings 6606and the outer dilator distal end. As a result of the relativedisplacement of the inner dilator 6610 with respect to the outer dilator6608, the sheath tip 6602 is no longer entrapped within free space 6603.Because the sheath distal tip 6602 is no longer entrapped, the sheath inturn relaxes to its natural unstretched state in which the sheathexpands, having a greater inner (and outer) diameter than in thestretched tensioned state. In its unstretched state the sheath can alsohave a shorter length than in its stretched tensioned state. In itsrelaxed unstretched state, the sheath relaxes over the outer dilator6608. The devices can be pulled through the sheath in a similar way,expanding the sheath to the stretched state as the devices go throughthe sheath and relaxing the sheath to the unstretched state after thedevices pass through.

FIG. 67 shows the configuration 6700 of the sheath system tip in a thirdposition. In configuration 6700, the inner dilator 6710 and the outerdilator 6708 is pushed toward a distal direction, such that the distaltip of the outer dilator 6708 extends beyond the sheath distal tip 6702.As shown in FIG. 67 there may still be a longitudinal gap between theinner dilator tip wings 6706 and the outer dilator distal end.

FIG. 68 shows the configuration 6800 of the sheath system tip in afourth position. In configuration 6800, the outer dilator 6808 has beenfurther pushed toward a distal direction such that the outer dilator6808 is now mated with the geometry of the inner dilator tip 6805, theinner dilator tip 6805 being held in place in its most distal position.As shown in FIG. 67 , outer dilator 6708 has a proximal portion and adistal portion, separated by a transition portion 6713, whichtransitions from the outer dilator proximal portion diameter to theouter dilator distal portion diameter. For example, the outer dilatorproximal portion has a diameter which is greater than a diameter of thedistal portion of the outer dilator 6708. For example, the transitionportion 6713 may be in the shape of a frustum, a cone, a concave orconvex shape, or any other geometry. The transition portion 6713 mayconsist of a substantially radial surface. The transition portion 6713on the outer dilator corresponds to a surface 6707 at the proximal endof the inner dilator tip wings 6706. For example, the surface 6707 maybe in the shape of a frustum, a cone, a concave or convex shape. Forexample, the surface 6707 may consist of a substantially radial surface.Contact between the surface 6707 and the surface 6713 prevents furthermotion of the outer dilator in the distal direction, and indicates thatthe inner dilator 6710 and outer dilator 6708 can be extracted as awhole. As shown in FIG. 68 , when the surface 6807 and the surface 6813are in contact, there may still be a longitudinal gap or free spacebetween the outer dilator distal end and the inner dilator tip wings.Configuration 6800 advantageously provides a relatively smooth or flushouter surface distal of the sheath distal tip 6802. This minimized lipallows for smooth retraction of the delivery system from the expandablesheath hub, as shown in FIG. 69 .

FIG. 69 shows the configuration 6900 of the sheath system tip in a fifthposition, where the inner dilator 6910 and outer dilator 6908 have beenpulled toward a proximal direction and are passing through the sheathbody, to be removed from the patient body.

In another implementation, the proximal end of the distal tapered tip ofthe inner dilator comprises a tapered diameter. FIG. 87 shows anadditional implementation of the delivery system tip in theconfiguration shown in FIGS. 65, 68, and 69 , while FIG. 89 shows anadditional implementation of the delivery system tip in theconfiguration shown in FIGS. 66 and 67 . FIG. 87 includes inner dilator8702 and outer dilator 8704. The proximal end of the distal tip of innerdilator 8902 as a tapered diameter. The tapered diameter allows forinner dilator 8702 to be pulled into outer dilator 8704 upon the releaseof the sheath from the delivery system tip, as discussed below in FIG.88 . As described below in relation to the delivery mechanismillustrated in FIGS. 83A-86D, in a first state, a second state, and afourth state of such implementations, the sheath is held in placebetween inner dilator 8702 and outer dilator 8704. Thus, the closing ofthe delivery tip system allows for the system to hold on to the sheathduring introduction of the sheath, until the sheath is inserted into thevasculature of a patient. Further, as described below in relation toFIGS. 90-93B, in a fourth state of the system, the closing of thedelivery tip system advantageously provides a seamless transitionbetween the dilators from which the sheath may be removed withoutgetting caught on the tip of the delivery system.

FIG. 89 shows the delivery system tip in a third state, described belowin relation to FIG. 88 . FIG. 89 similarly comprises inner dilator 8702and outer dilator 8704. In the third state, the inner dilator has beenmoved distal relative to the outer dilator. This motion between theinner dilator and the outer dilator may be attained using the tipinterlock described below in relation to FIGS. 22A-B, or using the innerand outer dilator hub described below in relation to FIGS. 83-85 . Thechanges in relative position of the elements of the sheath assembly asdescribed above in relation to FIGS. 65-69 can be attained byincorporation of the delivery mechanism shown in FIGS. 70-93B, anddescribed below.

FIGS. 22A and 22B show an introducer sheath assembly 2200 in twodifferent states. As shown in a first state in FIG. 22A (e.g. relaxedstate 404 of FIGS. 4A-B) expandable sheath body 202 has a first diameter2202 and a first length 2204. In one embodiment, the first diameter isbetween 3 mm and 8 mm, preferably between 3 mm and 6 mm, and preferably5.2 mm. In one embodiment, the first length is between 10 cm and 40 cm,preferably between 13 cm and 35 cm. Tensioning the introducer sheath 200into the elongated state shown in FIG. 22B, i.e. applying tensile forceson the introducer sheath via the dilator assembly 2000, reduces thesheath diameter to a second diameter 2208 and elongates the expandablesheath body 202 to a second length 2206. The expandable sheath body 202is locked into this configuration through tightening of the compressionnut 2016. Both the introducer sheath 200 and the dilator assembly 2000are inserted over a wire and into the desired position within thevasculature in this configuration, e.g. via a “Seldinger” or “modifiedSeldinger” technique.

In order to prevent movement of the inner dilator 2004 with respect tothe outer dilator 2002 during the movement of the introducer sheath 200with respect to the dilator assembly 2000 during the elongation setupstep described in relation to FIGS. 22A-B, a tip interlock is used tolock the tip 2006 with respect to the expandable sheath body 202. FIG.23A shows the distal end of the assembly with distal tip 2006 abuttingthe expandable sheath 202, while FIG. 23B shows the proximal end of theassembly, including a tip interlock 2018, inner dilator 2004, luer hub2020, and outer dilator 2002. The tip interlock 2018 has a width suchthat, when placed as shown in FIG. 23B onto the inner dilator 2004 andthe outer dilator 2002, at the distal end as shown in FIG. 23A, thedistal tip 2006 is locked in place against the expandable sheath 202.With the expandable sheath body 202 residing between the tip 2006 andthe outer dilator 2002, it is secured through a pinching force. Finally,locking the tip also prevents movement of the inner dilator 2004 withrespect to the outer dilator 2002.

FIGS. 24A-B show the next step in sheath deployment after the tipinterlock 2018 has been removed. When the tip interlock 2018 is removedfrom the inner dilator 2004, the pinching force holding the tip 2006 isremoved and the inner dilator 2004 is allowed to freely slide within theouter dilator 2002, as shown in FIG. 24B. On the proximal end of thedilator assembly 2000, as shown in FIG. 24A, the inner dilator 2004 ispushed forward with respect to the outer dilator 2002. Advancement ofthe inner dilator 2004 from proximal to distal causes the tip 2006 toseparate from the inner dilator 2004 and move distal to the expandablesheath body 202 on the distal end. Additional distal movement of theinner dilator 2004 independently of the outer dilator 2002 is notpossible—further forward movement results in inner dilator 2004 andouter dilator 2002 moving forward together.

FIGS. 25A-25C show removal of the dilator assembly, during which thedistal tip 2006 moves proximally back together against the outer dilator2002, resulting in a minimal proximal facing lip. FIG. 25A shows innerdilator 2004 and tip 2006 being moved distally in the direction of thearrow. FIG. 25B shows the inner dilator 2004 and tip 2006 being pulledback proximally until the tip 2006 abuts outer dilator 2002. FIG. 25Cshows the tip 2006, inner dilator and outer dilator being pulled backproximally until the tip 2006 abuts the expandable introducer sheathbody 202. Minimization of the lip between the tip 2006 and the outerdilator 2002 also minimizes the risk of the dilator assembly catching onthe expandable introducer sheath body 202 upon removal.

At least one advantage of the configuration discussed in relation toFIGS. 25A-C is being able to capture the distal tip of the expandableintroducer sheath while minimizing interference between the dilators andthe sheath upon removal (e.g. preventing buckling or kinking).Additional mating geometry on the outer surface of the outer dilator2002 may improve the lip further.

At the distal end of the sheath assembly, capture of the distal tip ofthe expandable sheath, as discussed above, can be achieved via variousdistal tip configurations. FIGS. 26-33 illustrate cross-sectional viewsof exemplary embodiments of the distal end, or tip, of the expandablesheath body 202. FIG. 26 illustrates a location marked as “last pick”2602 marking an end to the braid portion of the expandable sheath body202. In alternative configurations, the “last pick” 2602 may mark an endto a braid or an alternative expandable sheath body 202 material. Thereexists an additional length 2606 after the termination of the braidcomprising solely the polymer matrix material. This length can be equalto the inner diameter 2604. As shown in FIG. 26 , the thickness of thisregion 2608 can be equal to the wall thickness of the braid section ofthe expandable sheath body 202. Also shown, the inner diameter 2604 ofthe expandable sheath body 202 can be consistent throughout thistransition.

FIG. 27 shows a cross-sectional view of the distal end, or tip, of theexpandable sheath body 202. The inner diameter 2704 of the expandablesheath body 202 is labeled ID_(sheath). Also shown is a regioncomprising braid and polymer that reduces in diameter and wallthickness, ending at a final wall thickness and diameter 2708 labeled asID_(taper). This section is also defined by a taper angle 2706 labeled ataper. There exists an additional length after the termination of thebraid comprising solely the polymer matrix material terminating at adiameter 2710 labeled as 8 Fr. Alternatively, FIG. 28 shows across-sectional view of the tip where the braid terminates at the end ofthe tip. The “last pick” 2802 may mark an end to a braid or analternative expandable sheath body 202 material. Similar to theimplementation shown in FIG. 26 , there exists an additional length 2804after the termination of the braid comprising solely the polymer matrixmaterial. This length 2804 can be equal to the final wall thickness2806.

FIG. 29 shows a cross-sectional view of the delivery system distal tipwhere an inner supporting member 2902 and inner geometry of a distal tip2904 is assembled with the expandable sheath comprising a braidedsection 2906 and a polymer section 2908. The supporting member 2902 andthe distal tip 2904 create a gap 2910. Within the polymer section 2908there is a bump geometry 2912 that is also shown as a circular bump 2914when on the opposing wall of the sheath. The thickness of the polymersection 2908 and bump 2912 creates a thickness that is greater than thegap 2910. When the delivery system is at rest, there is no load on thecomponents. When there is axial strain on the expandable sheath, thedistal tip of the sheath is trapped inside of the volume created by thesupporting member 2902 and distal tip 2904 as the thickness cannot fitthrough the gap 2910. There may be a second set of bump 2914 further tothe distal end. The bump can be of a polymer that is the same as theencapsulating polymer.

FIG. 30 shows a cross-sectional view of the delivery system distal tipas shown in FIG. 29 as a variation where the previous bump 2912 is anelongate member 3002 within the polymer section 2908. The elongatemember 3002 has the advantage of having more material volume to fitthrough the gap 2910, decreasing the chances that the sheath cancompress and escape through with minimal impact to the sheath tipability to expand in the radial direction.

FIG. 31 shows a cross-sectional view of the delivery system distal tipas shown in FIG. 29 as a variation where the previous bump 2912 consistsof at least one circumferential ridge 3102 and lengthwise members 3104.The presence of the circumferential ridges 3102 is anticipated topotentially create pockets on an outer surface 3106 due to someprocessing methods. This embodiment further increases the volume anddecreases the chances that the sheath tip can compress and escapethrough the gap 2910 with some impact to the sheath ability to expand ina radial direction.

FIG. 32 shows a cross-sectional view of the delivery system distal tipas shown in FIG. 29 as a variation where the previous bump 2912 is aspiral elongate member 3202. This embodiment further increases thevolume and decreases the chances that the sheath tip can compress andescape through the gap 2910 with a minimized impact to the sheathability to expand in a radial direction.

FIG. 33 shows a cross-sectional view of the delivery system distal tipas shown in FIG. 29 as a variation where any of the previous concepts aspresented in FIGS. 29-32 could be in the braid area of the sheath. It isalso anticipated that the features described in FIGS. 29-32 could existin conjunction with FIGS. 26-28 . The bump 3302 can be a radio-opaquemarker that is welded to the braid. There can exist a section distal tothe feature that consists of the encapsulating polymer.

In order to facilitate the compatibility between the introducer sheath200 and dilator assembly 2000, the tip of the expandable sheath body 202may be configured to be compatible with the dilator tip interlockconfigurations discussed in relation to FIGS. 34-42 . FIGS. 34-42illustrate cross-section views of dilator tip and sheath captureconfigurations. The tip capture mechanism may comprise a detent (a catchpreventing motion until release), layer, slug, or o-ring configuration,described in relation to FIGS. 34-37 . For example, FIG. 34 shows adetent configuration 3400 both before (A) and after (B) tip capture,with a dilator body 3402 being inserted into a dilator tip 3406. Thedilator body 3402 may be rigid while the dilator tip may be semi-rigid.The dilator body 3402 has a semi-elastic compression band 3404 that iscaptured by the dilator tip 3406 after insertion. Protrusion 3410 andpocket 3414 allow for capture and retention of the distal end of sheathbody 202 by providing circumferential compression 3412. The outerportion 3408 of the semi-rigid dilator tip 3406 can comprise a softmaterial for flexibility or a rigid material for inflexibility.

FIG. 35 shows a layer configuration 3500 before (A) and after (B) arigid dilator body 3502 is inserted into a semi-rigid dilator tip 3506.The semi-rigid dilator tip 3506 has a semi-elastic compression layer3504 that captures the rigid dilator body 3502 after insertion. Thesemi-elastic compression layer 3504 allows for capture and retention ofthe distal end of sheath body 202 by providing compressive retentionwith two faces 3508.

FIG. 36 shows a slug configuration 3600 before (A) and after (B) a rigiddilator body 3602 is inserted into a soft-flexible dilator tip 3604. Thesoft-flexible dilator tip 3604 has an elastomeric slug 3608 within asemi-rigid reinforcement 3606 that captures the rigid dilator body 3602after insertion. The elastomeric slug 3608 is compressed to allow forspace during insertion of the rigid dilator body 3602. Once insertedinto the semi-rigid reinforcement 3606, the distal end of the sheathbody 202 is retained by the compressive forces of the face 3610 of thesemi-rigid reinforcement.

FIG. 37 shows an o-ring configuration 3700 before (A) and after (B) arigid dilator body 3702 is inserted into a rigid dilator tip 3704. Therigid dilator tip 3704 has a floating o-ring 3706 that flexes to allowfor the rigid dilator body 3702 to be inserted into the rigid dilatortip 3704. Once inserted, the floating o-ring 3706 appliescircumferential compression 3708 which retains the distal end of thesheath body 202 when inserted.

Alternatively, the tip capture mechanism may also comprise a ribbed,beaded, or split ring configuration, described in relation to FIGS.38-41 . FIG. 38 shows a ribbed configuration 3800 before (A) and after(B) a distal end of a sheath body 202 and a rigid dilator body 3802 areinserted into a rigid dilator tip 3804. The distal end of the sheathbody 202 has soft thermoplastic ribs 3806 that are sized to fit intocavities 3808 inside the rigid dilator tip 3804. Once inserted, thecavities 3808 capture the soft thermoplastic ribs 3806 and retain thesheath body 202 within the rigid dilator tip 3804.

FIG. 39 shows a beaded configuration 3900 before (A) and after (B) adistal end of a sheath body 202 and a rigid dilator body 3902 areinserted into a rigid dilator tip 3904. The distal end of the sheathbody 202 has beads 3906 that are sized to fit into pockets 3908 insidethe rigid dilator tip 3904. In one configuration, the beads 3906 arewelded to the sheath body 202. Once inserted, the pockets 3908 capturethe beads 3906 and retain the sheath body 202 within the rigid dilatortip 3904.

FIG. 40 shows a split ring configuration 4000 before (A) and after (B) adistal end of a sheath body 202 and a rigid dilator body 4002 areinserted into a rigid dilator tip 4004. The distal end of the sheathbody 202 has a semi-elastic split ring 4006. Once inserted, thesemi-elastic split ring 4006 is captured between an inner wall 4008 ofthe rigid dilator tip 4004 and the rigid dilator body 4002.

FIG. 41 shows a suture loop configuration 4100 before (A) and after (B)a distal end of a sheath body 202 and a rigid dilator body 4102 areinserted into a rigid dilator tip 4106. The distal end of the sheathbody 202 has a suture loop 4104 that is trapped or captured in a detent4108 inside the rigid dilator tip 4106 once inserted. The suture loopfeeds 4110 run along the outer portion of the sheath body 202.

FIG. 42 shows a cross-section view of a configuration 4200 using adistal end of a sheath body 4204 (as shown in FIG. 29 ) with a dilatorbody 4206 and a dilator tip 4202. The distal end of the sheath body 4204has a bump geometry 4208 that may have a range of movement in aproximal-distal direction, but this range of movement is limited bycontact between the bump geometry 4208 against the dilator tip 4202,and/or contact between the bump geometry 4208 against the distal end ofthe dilator body 4206. Configuration 4200 allows for the sheath body4204 to be trapped or captured between the dilator body 4206 and thedilator tip 4202. The bump geometry 4208 may be any geometry that limitsthe range of motion of the sheath body 4204 by abutting against thedilator body 4206.

At the proximal end of the sheath assembly, connection of the sheath isachieved via a hub. As discussed in relation to FIG. 1 , the introducersheath 200 has a hub 204 that allows for connection with a dilatorassembly 2000 and a hemostasis stylet assembly 4600. In addition, thehub 204 attaches to the expandable sheath body 202. FIG. 43 shows theattachment of the expandable sheath body 202 to the hub 204 of theintroducer sheath 200. First, the expandable sheath body 202 is slid upa taper of the hub 204 (A). Second, a locking ferule 4302 is insertedwhich has fingers 4304 that interlock with geometry on the hub 204 (B).A locking cap 4306 is then twisted on which creates a pinching forcebetween the hub 204 and the locking ferule 4302. The fingers of thelocking ferule 4302 prevent rotation, therefore preventing rotationalloading on the sheath body 202 during the locking cap attachment. Alsoshown is a cap 4308 to provide containment of the hemostasis valve whichis not shown. FIG. 44 shows a cross-sectional side view of theintroducer sheath hub 204 and introducer sheath 202.

FIG. 45 shows a second expandable sheath hub 204 with a series offingers 4502. The fingers 4502 are design to provide additional supportthrough the region of the expandable sheath body 202 where ittransitions form the large diameter secured on the hub 204 to a secondsmaller diameter. This area is typically an area of low mechanicalintegrity due to the transition. The fingers 4502 contain geometry thatallows them to flex open to pass the pump 4504. The fingers 4502 containa curved distal edge 4506 to allow for the withdrawal of the pump 4504.The fingers 4502 contain a geometry that prevents them from collapsingpast a minimum diameter as the fingers 4502 make contact with eachother. The hub 204 has an area that contains a hemostasis valve 4508.Also shown is a port 4510 for a sidearm (not shown) and luer connection(not shown) used for flushing and aspirating the introducer sheath 200.

At least one advantage of the hub and sheath assembly is to minimize therisk of sheath eversion at the hub, i.e. reduce the risk during removalof the device for the sheath to either ever and fold inside out from thehub or gather around the inside edge and bunch up, preventing furtherremoval.

FIGS. 70-81 show cross-sections of an illustrative sheath deliverysystem. FIG. 70 shows a cross-section of a configuration 7000 of theexpandable sheath delivery system in a first position. Sheath deliverysystem 7000 includes snap ring 7002, handle 7004, outer dilator hub7006, a pair of actuators 7008, a slider 7010, an inner dilator hub7012, and a carrier 7014. Not shown in configuration 7000 are a pair ofconnectors 7016 that connects the slider to the carrier.

FIG. 71 shows a cross-section of a configuration 7100 of the expandablesheath delivery system in a transitional position between the firstposition of configuration 7000 and a second position of configuration7200, shown in FIG. 72 . In configuration 7100, the user pinches theactuators 7102 which depresses latches 7104 on the handle 7004 thatallows the slider 7010 to move. While the actuators 7102 are depressed,the user slides the slider forward to the second position in FIG. 72 .

In configuration 7200, shown in FIG. 72 , the sheath delivery system isin the second position and shows the point in which the inner dilatorhub 7012 makes contact with the outer dilator hub 7006. FIG. 72 shows across-section of another configuration 7300 of the sheath deliverysystem in the second position. In the second position, the outer dilatorhub 7006 is constrained by a feature on the inside of the handle 7004. Aforce is required to overcome the feature which serves to keep the outerdilator from moving forward during the transition from the firstposition to the second position.

FIG. 74 shows a cross-section of a configuration 7400 of the sheathdelivery system in a third position. A positive stop on the innerdiameter of the handle 7004 is shown which prevents the movement of theinner dilator hub 7012 forward.

FIG. 75 shows an illustrative view of a line defining the off-verticalcross-section of FIG. 74 . FIG. 76 shows the delivery system in thethird position where the outer dilator hub 6906 has overcome the featureon the inner diameter of the handle 7004.

FIG. 77 shows the delivery system with a horizontal cross-section,having a pocket in the delivery system handle 7004 that allows latcheson the carrier 7014 to open and detach from the inner dilator hub.

FIG. 78 shows the delivery system in a fourth position where the forwardmovement of the slider now creates movement forward of the outer dilatorassembly only and the inner dilator assembly no longer moves.

FIG. 79 shows the delivery system in a fifth position where the outerdilator hub 7006 has been moved to its most forward location and hasmade contacts with features on the snap ring 7002 that causes the armsto flex and features on the inner surface to no longer constrain thesheath hub.

FIG. 80 shows a vertical cross-section including the final position ofthe slider 7010 where latches on the handle 7004 engage an opening onthe slider 7010, preventing further movement in either direction. FIG.81 shows the retraction of the delivery system in the proximal directionfrom the expandable sheath hub.

FIG. 82 shows an isometric view of an illustrative delivery mechanism8200 comprising sheath 8202, hub 8204, hub housing 8206, trigger 8208,slider 8210, and outer dilator 8212. Delivery mechanism 8200 may be anyone of system 6000 of FIG. 60 , system 6100 of FIG. 61 , system 6200 ofFIG. 62 , or Figure system 6300 of FIG. 63 . Delivery mechanism 8200 isconfigured to insert sheath 8202 (e.g., expandable sheath 200 of FIG. 2or sheath 2200 of FIGS. 22A-22B) into the vasculature of a patient bymeans of a series of dilators and respective hubs, namely an innerdilator (not shown) and outer dilator 8212. Such implementations havingdilator hubs differ from previously discussed implementations having adilator tip interlock used to adjust the relative motion of thedilators. Hub 8204 and hub housing 8206 contain elements that areconfigured to adjust the relative positions of sheath 8202 and theseries of dilators, including outer dilator 8212. The dilators areconfigured to extend from a distal end of hub 8204. Hub housing 8206extends in a proximal direction from hub 8204. Hub housing 8206 isaffixed to trigger 8208 and slider 8210. Trigger 8208 is configured tobe depressed, and trigger 8208 is connected to hub housing 8206 at thedistal end of trigger 8208. When trigger 8208 is depressed, it rotatesabout the point at which it is connected to hub housing 8206. In theillustrative state shown in FIG. 82 , trigger 8208 is depressed, suchthat the proximal end of trigger 8208 is in contact with a proximalportion of hub housing 8206. The depression of trigger 8208 draws downsheath 8202 prior to the insertion of sheath 8202 into a patient. Slider8210 is configured to adjust the relative positions of the dilators andsheath 8202. FIG. 82 shows a state in which sheath 8202 is attached tothe distal end of the hub 8204. The combination of these elementsadvantageously ensure that the sheath is drawn down prior to theinsertion of the sheath into the patient, preventing the possibilitythat the operator of the device forgets to draw down the sheath prior toattempting to insert the device into the vasculature of the patient.Additionally, these elements, as described below in relation to FIGS.83A-92 , advantageously prevent the accidental deployment of the sheathduring preparation for insertion.

FIGS. 83A and 83B show two illustrative cross-sectional views of anillustrative delivery mechanism 8300 for an expandable sheath (i.e.,sheath 200 of FIG. 2 or sheath 2200 of FIGS. 22A-22B). FIG. 83A shows across-sectional view of an illustrative delivery mechanism 8300comprising sheath 8302, hub 8304, hub housing 8306, trigger 8308, slider8310, clip 8312, slider slots 8314, and pins 8316. Illustrative deliverymechanism 8300 may, for example, be delivery mechanism 8200 of FIG. 82 .In FIG. 83A, delivery mechanism 8300 is shown in a first state. In thisfirst state, trigger 8308 is undepressed. Further, in this state, sheath8302 is in a free state, hub 8304 is locked to hub housing 8306 andslider 8310 is locked in position. As described further below inrelation to FIGS. 88-93B, the motion of slider 8310 is configured todirect pins 8316 through slider slots 8314. Each of pins 8316 is affixedto a dilator hub (an inner dilator hub and an outer dilator hub). Whenslider 1310 is moved in a distal direction, the forces exerted on pins8316 by slider slots 8314 cause pins 8316, and thus the respectivedilator hubs to which each of pins 8316 is connected (described below inrelation to FIGS. 84A-85B), to move relative to each other. The relativemotion of the dilator hubs in turn causes relative motion of the innerand outer dilators. This simplifies the motion that is required relativemotion between the two dilators, as the entirety of the desired motionis attained upon the sliding of slider 8310.

FIG. 84A shows an illustrative cross-sectional view of an illustrativedelivery mechanism 8400 for the insertion of an expandable sheath havingan inner dilator hub and an outer dilator hub wherein the system is inthe first state described above in relation to FIG. 83A. Illustrativedelivery mechanism 8400 may be, for example, one of illustrativedelivery mechanism 8200 of FIG. 82 or illustrative delivery mechanism8300 of FIG. 83 . Illustrative delivery mechanism 8400 comprises clip8402, housing lock 8404, trigger 8406, outer dilator hub 8408, innerdilator hub 8410, and hub housing 8412. As previously discussed inrelation to FIG. 83B, outer dilator hub 8408 and inner dilator hub 8410are each connected to pins within the hub housing (e.g., pins 8316 ofFIG. 83B). Clip 8402 is configured to engage housing lock 8404 when hubhousing 8412 is moved in a proximal direction as the device is movedfrom the first state to the second state. Depression of trigger 8406while the system is in the first state causes hub housing 8412 to movein a proximal direction. The depression of trigger 8406 and the relativemotion of the dilators attained by the motion of the slider (not shown)simplifies the burden of the practitioner to position the dilatorscorrectly relative to one another, while simultaneously preventing thedevice from being inserted into the patient prior to the sheath beingdrawn down. This in turn prevents undue injury unto the patient duringthe insertion of an expandable sheath or other device into thevasculature of the patient.

FIG. 83B shows a cross-sectional view of illustrative delivery mechanism8300 comprising sheath 8302, hub 8304, hub housing 8306, trigger 8308,slider 8310, clip 8312, slider slots 8314, and pins 8316 in a secondstate. In this second state, trigger 8308 is depressed, and,correspondingly, sheath 8202 is drawn down. Depression of trigger 8308causes hub housing 8306 to move in the proximal direction. As shown inFIG. 83 , the center of rotation about which trigger 8308 rotates isbelow the point of contact between trigger 8308 and the proximal surfaceof hub housing 8306. When trigger 8308 is depressed, the proximal end oftrigger 8308 pushes against a proximal surface of hub housing 8308.

FIG. 84B shows an illustrative cross-sectional view of an illustrativedelivery mechanism 8400 for the insertion of an expandable sheath havingan inner dilator hub and an outer dilator hub wherein the system is inthe second state described above in relation to FIG. 83B. FIG. 84B showsillustrative delivery mechanism 8400 wherein trigger 8406 has beendepressed and hub housing 8412 has moved in a proximal direction. Theproximal motion of hub housing 8412 causes the pins attached to outerdilator hub 8408 and inner dilator hub 8408 to move, causing relativemotion between outer dilator hub 8408 and inner dilator 8410.Additionally, the proximal motion of hub housing 8412 causes clip 8402to engage housing lock 8404. The engaging of housing lock 8404 byhousing 8412 advantageously keeps the sheath drawn down after theoperator of the delivery mechanism depresses the trigger.

FIGS. 85A and 85B show two illustrative views of an illustrativedelivery mechanism for the insertion of an expandable sheath wherein theinner dilator hub contains a luer blocker. FIG. 85A shows anillustrative luer-blocking mechanism comprising inner dilator hub 8502,luer blocker 8504, housing cam slot 8506, luer blocker camshaft 8508,inner dilator 8510, and outer dilator 8512. Inner dilator hub 8502contains luer blocker 8504. Luer blocker 8504 comprises luer slot 8514and luer blocker camshaft 8508 which extends into housing cam slot 8506.Luer blocker 8504 is shown in a first state in FIG. 85A, in which luerblocker camshaft 8508 is disposed at the proximal end of housing camslot 8506. In this first state of luer blocker 8504, luer slot 8514 isnot aligned with an axis of the dilators. As a result, in the firststate of luer blocker 8504, it is not possible to insert a guidewirethrough the device. As shown in FIG. 85B, in a second state, luerblocker camshaft 8508 is moved in the distal direction. Movement of luerblocker camshaft 8508 in the distal direction within housing cam slot8506 from the first state to the second state causes a quarter rotationof luer blocker 8504. The quarter rotation of luer blocker 8504 causesluer slot 8514 to align with an axis of the dilators, allowing theinsertion of a guidewire through the mechanism. Luer blocker 8504 andluer slot 8514 thus together advantageously prevents the accidentalpassage of a guidewire through the device prior to the sheath beingdrawn down. This is beneficial to the patient, as insertion of theguidewire through the device prior to the sheath being drawn downreduces the benefits of inserting the sheath at a low profile. As such,the guidewire is inserted once the sheath is drawn down, leading tolower rates of vascular injury and damage, lower required insertionforces, and less necessary predilation.

FIGS. 86A-8D show illustrative cross-sectional views of the hub housingof an illustrative delivery system for an expandable sheath, the hubhousing containing a locking mechanism on the slider of the hub housing.FIG. 86A shows an illustrative cross-sectional view of the hub housing8600 of a delivery mechanism for the insertion of an expandable sheath.For example, section view of the hub housing 8600 may show a sectionview of hub housing 8206 of FIG. 82 , hub housing 8306 of FIG. 83 , hubhousing 8412 of FIG. 84 . Hub housing 8600 comprises hub housingcomponent 8602, slider locking feature 8604, slider 8606, sectionedplane 8608, and housing side 8610. In the illustrative example shown,housing side 8610 is the right side of the housing when viewed from theproximal direction. Slider locking feature 8604 can, for example, beseen below slider 8310 of FIG. 83A. In general, the delivery mechanismmay be constructed such that slider locking feature 8604 is disposed oneither the left side or the right side of the delivery mechanism whenviewed from the distal direction. In other words, the delivery mechanismmay be constructed as a mirror image of the illustrative implementationsdiscussed herein. Slider locking feature 8604 engages with a portion ofhub housing 8600. In the first state of slider 8606, as discussedpreviously in relation to FIG. 83A, slider locking feature 8604 ofslider 8606 is trapped by the portion of the hub housing 8600 and isunable to move. Additionally, FIG. 86A shows hub housing component 8602in abutment with slider 8606. As previously discussed in relation toFIGS. 83B and 84A, hub housing component 8602 is configured to move inthe proximal direction upon depression of the trigger of the deliverysystem. The proximal motion of hub housing component 8602 allows sliderlocking feature 8604 to move. This advantageously prevents the motion ofthe slider prior to the sheath being drawn down.

FIG. 86B shows an illustrative top view of the cross-sectional view ofhub housing 8600 of a delivery mechanism for the insertion of anexpandable sheath shown in FIG. 86A. Hub housing 8600 comprises hubhousing component 8602, slider locking feature 8604, slider 8606,sectioned plane 8608, housing side 8610, and hub housing pin 8612. Themovement of hub housing component 8602 in the proximal direction isconstrained such that hub housing pin 8612 slides through the gap in hubhousing component 8602.

FIGS. 86C and 86D show an illustrative cross-sectional view and anillustrative aerial cross-sectional view, respectively, of the hubhousing 8600 of a delivery mechanism for the insertion of an expandablesheath. For example, section view of the hub housing 8600 may show asection view of hub housing 8206 of FIG. 82 , hub housing 8306 of FIG.83 , hub housing 8412 of FIG. 84 . Hub housing 8600 comprises hubhousing component 8602, slider locking feature 8604, slider 8606,sectioned plane 8608, housing side 8610, and pump housing pin 8612. Themovement of hub housing component 8602 in the proximal directioneliminates the abutment of hub housing component 8602 with slider 8606.Housing component 8602 thus slides in the proximal direction towards thegap formed in housing side 8610. The proximal motion of housingcomponent 8602 thus enables slider locking feature 8604 to be releasedand allows the motion of the slider, and thus the adjustment of therelative position of the two dilators, after the trigger is depressedand the sheath is drawn down.

FIG. 88 shows a cross-sectional view of an illustrative deliverymechanism 8800 for the introduction of an expandable sheath in a statewherein the inner and outer dilator hubs are positioned to release anexpandable sheath. Delivery mechanism 8800 comprises sheath 8802, hub8804, hub housing 8806, trigger 8808, slider 8810, clip 8812, sliderslots 8814, and pins 8816. Illustrative delivery mechanism 8800 may, forexample, be delivery mechanism 8200 of FIG. 82 . In FIG. 88 , deliverymechanism 8800 is shown in a third state. In this third state, trigger8808 is depressed, hub housing 8806 has moved in a proximal directionrelative to the first state (as described above), and slider 8810 hasmoved in the distal direction. Movement in the distal direction ofslider 8810 causes relative motion of the inner and outer dilators, asslider slots 8814 guide pins 8816 through slider slots 8814 as hubhousing 8806 moves in a proximal direction. The relative geometries ofslider slits 8814 can be configured to adjust the relative motionbetween the inner and the outer dilators. In certain implementations,the inner dilator moves forward by an amount, as discussed previously inrelation to FIG. 89 , while the outer dilator remains stationaryrelative to hub housing 8806. The relative motion between the twodilator hubs allows the sheath to be released from between the innerdilator hub and the outer dilator hub. As such, the inner dilator huband outer dilator hub can be withdrawn in order to remove the deliverysystem mechanism. In some implementations, the inner dilator movesforward by between about 2 millimeters and about 10 millimeters. Incertain implementations, the inner dilator moves forward by betweenabout 4 millimeters and about 8 millimeters. In further implementations,the inner dilator moves forward by about 6 millimeters. The relativemotion of the inner and the outer dilators can be adjusted based on therespective lengths of the dilators.

FIG. 90 shows a cross-sectional view of an illustrative deliverymechanism 9000 for the introduction of an expandable sheath in thefourth state wherein the inner and outer dilator hubs are positioned tobe withdrawn from the sheath. Delivery mechanism 9000 comprisescomprising sheath 9002, hub 9004, hub housing 9006, trigger 9008, slider9010, clip 9012, slider slots 9014, pins 9016, inner dilator hub 9018,and outer dilator hub 9020. Illustrative delivery mechanism 9000 may,for example, be delivery mechanism 8200 of FIG. 82 . In FIG. 88 ,delivery mechanism 9000 is shown in a fourth state. In this fourthstate, trigger 8808 is depressed, slider 8810 has moved as far aspossible in the distal direction, and hub housing 9006 has moved in aproximal direction relative to the first state, described above. Asdiscussed, movement in the distal direction of slider 9010 causesrelative motion of the inner and outer dilators, as slider slots 9014guide pins 9016 connected to inner dilator hub 9018 and outer dilatorhub 9020 through slider slots 9014 as hub housing 9006 moves in aproximal direction. The relative geometries of slider slits 9014 can beconfigured to adjust the relative motion between the inner and the outerdilators. Between states 3 and states 4, as discussed in relation toFIG. 88 and FIG. 90 , the inner dilator remains stationary, and thesheath is released from being held by the inner dilator hub and theouter dilator hub as the pin 9016 to which inner dilator hub 9018 isattached moves freely through slider slot 9014. However, between FIGS.88 and 90 , outer dilator hub 9020 continues to move in the distaldirection due to the fact that pin 9016 to which outer dilator hub 9018is connected is in contact with the proximal end of its correspondingslider slot 9014. This distal motion of outer dilator hub 9018 bringsthe tip of the delivery system back to a closed position, as shown, forexample, in FIG. 87 , allowing the inner dilator hub and the outerdilator hub to be withdrawn while leaving the sheath drawn down.

As previously discussed in relation to FIG. 84B, relative motion of theinner and outer dilators is attained by guiding pins attached to each ofthe inner and outer dilators through slider slots. FIG. 91 shows anillustrative cross-sectional view of hub housing 9100 comprising innerdilator hub 9102, outer dilator hub 9104, inner dilator hub pin 9106,and outer dilator hub 9108. Inner dilator hub pin 9106 and outer dilatorhub pin 9108 are configured to slide within the slider slots, aspreviously discussed, and are also configured to slide up and downwithin their respective hubs.

FIG. 92 shows an illustrative internal view of the hub housing 9200 of adelivery mechanism for an expandable sheath. Hub housing 9200 housespins 9202 and slider slots 9204. Movement of the slider (not shown) inthe longitudinal direction guides pins 9202 through slider slots 9204.One of pins 9202 is connected to the inner dilator hub, and the otherpin is connected to the outer dilator hub. This motion of pins 9202through slider slots 9204 creates relative motion between the inner andouter dilator hubs, which, in turn, creates relative motion between theinner and outer dilators themselves. Slider slots 9204 may alternativelybe disposed within the housing side, as previously discussed in relationto FIGS. 86A-D. The slider slots, the slider, and the channel in thedilator advantageously control the timing, direction, and extent of themovement of the dilators. This facilitates operation of the device forthe user, as several specific movements of the components are achievedusing a single motion of the slider, ultimately resulting in the releaseof the sheath tip for the user.

FIGS. 93A and 93B show an illustrative cross-section view of the hubhousing of an illustrative delivery mechanism for the insertion of anexpandable sheath. FIG. 93A shows the mechanism in the first, second,and third states. FIG. 93B shows the mechanism in the fourth state.FIGS. 93A and 93B FIG. 93A shows an illustrative cross-sectional view ofthe hub housing 9300, including hub 9302, dilator 9304, clips 9306, andcollar 9308. Clips 9306 further comprise securement teeth 9310. Hubhousing 9300 is disposed distal of hub 9302. Hub housing 9300 and hub9302 are configured to receive dilator 9304. In the illustrativeimplementation showed in FIG. 93 , dilator 9304 is an outer dilator. Hubhousing 9300 further comprises clips 9306. Clips 9306 secure hub 9302within hub housing 9300 when the device is in the first state, thesecond state, and the third state, and discussed previously in relationto FIGS. 83A, 83B, and 88 , respectively. Clips 9306 are operated by aspring. Outer dilator 9304 further comprises collar 9308, which, in thefirst state, the second state, and the third state, is not engagedaround outer dilator 9304.

FIG. 93B shows an illustrative cross-sectional view of the hub housing9300 in the fourth state, as discussed previously in relation to FIG. 90. FIG. 93B includes hub 9302, dilator 9304, clips 9306, collar 9308, andsecurement teeth 9310. In the fourth state, collar 9308 contacts clips9306. The contact between clips 9306 and collar 9308 causes clips 9306to pivot in order to remove securement teeth 9310 from the hub. Removalof the securement teeth 9310 from the hub allows the delivery mechanismto be removed from the hub.

FIGS. 94A-96C show an alternative embodiment of a delivery mechanism foran expandable sheath. FIG. 94A shows an isometric view of anillustrative delivery mechanism 9400 for an expandable sheath. Deliverymechanism 9400 comprises dilator 9402, hub 9404, hub housing 9406, andkeys 9408. FIG. 94B shows delivery mechanism 9400 from a side view. Asshown in FIG. 94C, in implementations having the delivery mechanismshown in FIGS. 94A and 94B, the sheath is drawn down into the firststate of the device when hub 9404 is pushed into hub housing 9406 in thedistal direction. Keys 9408 then snap in place within hub housing 9406to keep the sheath drawn down. As shown in FIG. 94D, hub housing 9406 istwisted 90 degrees to transition from the second state and third states,in which the tip of the delivery mechanism is deployed, to the fourthstate, in which the delivery mechanism can be released from the hub.

FIG. 95 shows an illustrative view of the delivery mechanism 9500comprising hub 9502, barrel 9504, slots 9506, lumen 9508, and pins 9510.Relative motion of the inner and outer dilators along the longitudinalaxis of delivery mechanism 9500 is controlled by the interaction betweenpins 9510 and slots 9506 in barrel 9504. A rigid inner member (notshown) is affixed to the inner dilator and the outer dilator andprevents the dilators from turning as pins 9510 traverse the pathsdefined by slots 9506 in barrel 9504. This implementation similarlyallows for the relative motion of the inner dilator and the outerdilator to be adjusted, while preventing the insertion of the sheathprior to the sheath being drawn down by the proximal motion of hub 9404into hub housing 9406 by being configured to progress through the first,second, third, and fourth states, as previously discussed in relation toFIGS. 83A, 83B, 88, and 90 .

FIGS. 96A-C show an illustrative hub release drum 9600 comprising key9602, hub 9604, and hub housing 9406. Once the device is drawn down bythe pushing of hub 9404 into hub housing 9406, key 9602 interacts withhub release drum 9600 to lock hub 9404 in place with respect to hubrelease drum 9600. As shown in illustrative FIG. 96B, hub release drum9600 blocks an outward extending portion of hub 9604, locking hub 9604in place. Once the device is in the fourth state (i.e., once the deviceis releasable from hub 9604), hub release drum 9604 aligns with theoutward features of hub 9604, allowing the removal of the deliverymechanism from hub 9604.

As discussed above in relation to FIG. 1 and sheath assembly 100, and inrelation to FIGS. 20-25 , the expandable sheath 200 is used incombination with a dilator assembly 2000 to expand the opening of theblood vessel of a patient, and once the dilator assembly 2000 is removedfrom the expandable sheath 200, the expandable sheath 200 can be used incombination with a hemostasis stylet. A hemostasis stylet assembly canbe used to regulate hemostasis between the opening of the blood vesseland the expandable sheath body 202. In some implementations, thehemostasis stylet can be a repositioning sheath, which is also used tocontrol of the blood flow along the expandable sheath and minimizebleeding. A method of regulating hemostasis between the opening of theblood vessel and the expandable sheath body 202 using a hemostasisstylet assembly is described above in relation to FIG. 19 . FIG. 1Bshows a sheath assembly including an introducer sheath 200 (as describedin FIG. 2 ) connected to the hemostasis stylet assembly 4600 (asdescribed in FIG. 46 ). FIG. 46 shows a hemostasis stylet assembly 4600with a catheter 4602 of a pump. The hemostasis stylet assembly 4600consists of a locking cap 4604, locking hub body 4606 with a set ofactuators, e.g. opposing buttons 4608. When the buttons 4608 arecompressed inward, the locking hub body 4606 and attached componentsslide freely on the catheter 4602. When the buttons 4608 are left free,the locking hub body 4606 and attached components are fixed on thecatheter 4602. The proximal end of the locking hub body 4606 isconnected to an attachment component 4610 of a first sterile layer 4612.The first sterile layer 4612 is defined by an inner diameter and outerdiameter defining a thin layer with a proximal end and a distal end. Thehemostasis stylet body 4614 resides within the first sterile layer 4612and is defined by an outer diameter, inner diameter, and distal andproximal end. The inner diameter of the hemostasis stylet body 4614aligns axially and clears the catheter 4602. The first sterile layer4612 is connected to the distal end 4616 of the hemostasis stylet hub4618. The hemostasis stylet body 4614 is also connected to the distalend 4616 of the hemostasis stylet hub 4618. The hemostasis stylet hub4618 contains an internal lumen connecting the distal portion incommunication with the lumen of the hemostasis stylet body 4614 andproximally with an internal seal component that seals on the outerdiameter of the catheter 4602. The hemostasis stylet can slide along thecatheter 4602. The proximal portion of the hemostasis stylet hub 4618 isconnected to an attachment component 4620 of a second sterile layer4622. The catheter 4602 is visibly within the second sterile layer 4622.The proximal portion of the second sterile layer 4624 may be attached toanother component. In some implementations, the first sterile layer 4612and second sterile layer 4624 can be sterile sleeves that protectcatheter 4602.

FIG. 47 shows the hemostasis stylet assembly 4600 (as described in FIG.46 ) and an introducer sheath 200 (as described in FIG. 2 ). Also shownin FIG. 47 is a pump after insertion through the introducer sheath 200.In some implementations, the pump and the introducer sheath can beassembled and packaged together prior to insertion in the body of apatient. In FIG. 47 , the hemostasis stylet assembly 4600 is notattached to the introducer sheath 200. As shown in FIG. 47 , a gap 4730exists between the hemostasis stylet assembly 4600 and the introducersheath 200, and catheter 4602 is exposed between the hemostasis styletassembly 4600 and the introducer sheath 200. In some implementations,gap 4730 can be covered using a sterile layer or a sterile sleeve 4612.In order to keep the catheter 4602 sterile and use the hemostasis styletassembly 4600 (or repositioning sheath), the portion of exposed catheter4602 corresponding to gap 4730 is advantageously covered by sterilesleeve 4612. In this configuration, the sterile sleeve extends from thehemostasis stylet hub 4618 to the locking hub body 4606.

Similar to FIG. 1B, FIG. 48 shows the hemostasis stylet assembly 4600(as described in FIG. 46 ) connected to an introducer sheath 200 (asdescribed in FIG. 2 ). The connection is achieved by locking hub 204 ofthe introducer sheath 200 to locking cap 4604 of the hemostasis styletassembly 4600 and locking catheter 4602 to the introducer sheath 200.The locking mechanism between the locking hub 204 and the locking cap4604 can be, for example, a twist lock, pop, or any comparable lockingmechanisms. In some implementations, the locking mechanism between thehemostasis stylet assembly 4600 and the introducer sheath 200 can bedifferent from the locking mechanism between the catheter 4602 and theintroducer sheath 200. The proximal end of the sterile layer 4612 isconnected to the distal end of the hemostasis stylet hub 4618. Thedistal end of the sterile layer 4612 is connected to the proximal end4610 of the locking hub body 4606. As shown in FIG. 48 , there is noexposed catheter between the hemostasis stylet assembly 4600 and theintroducer sheath 200.

At least one advantage of integrating the hemostasis stylet assembly4600 with the introducer sheath 200 is that the integration allows fortitrated hemostasis at the opening of the blood vessel, e.g.arteriotomy. The diameter of the hemostasis stylet can be specificallychosen to fill the opening of the blood vessel so that distal blood flowis not sacrificed for hemostasis.

In one configuration, the hemostasis stylet assembly 4600 terminateswithin the body of the introducer sheath 200. In another configuration,the hemostasis valve distal end may terminate outside of the introducersheath 200. The hemostasis valve may have a constant diameter. Thehemostasis valve may have a constant diameter with a short taper at thedistal tip. The hemostasis valve may have a long taper along its length.The hemostasis valve may have a first diameter at the distal end, ataper in the middle, and a second diameter at the proximal end with thefirst diameter smaller than the second diameter. The hemostasis valvemay have a locking mechanism to attach the hemostasis stylet assembly4600 to the introducer sheath hub 204. When the pump 502 is insertedthrough the expandable sheath body 202 the expanded section passesthrough and potentially stretches the opening of the blood vessel. Ifthe vessel, e.g. artery cannot recover all of the expansion, thehemostasis stylet assembly 4600 will provide a means of filling theenlarged vessel opening to achieve hemostasis between the vessel and theexpandable sheath body 202.

In view of the foregoing, the person of ordinary skill will appreciatethat the present disclosure provides a means to fixate mechanicaldevices in place within an expandable sheath, thereby preventing themigration of the device once inserted into the heart. Medical devices ofvarying diameters may be used with a single expandable sheath.

The foregoing is merely illustrative of the principles of thedisclosure, and the systems, methods, and devices can be practiced byother than the described embodiments, which are presented for purposesof illustration and not of limitation. It is to be understood that thesystems, methods, and devices disclosed herein, while shown for use in asystem for intracardiac heart pumps, may be applied to systems, methods,and devices for other implantable heart pumps or implantable cardiacassist devices.

Variations and modifications will occur to those of skill in the artafter reviewing the present disclosure. The various features describedor illustrated above, including any components thereof, may be combinedor integrated in other systems. Moreover, certain features may beomitted or not implemented. The various implementations described orillustrated above may be combined in any manner.

Examples of changes, substitutions, and alterations are ascertainable byone skilled in the art and could be made without departing from thescope of the information disclosed herein. All references cited hereinare incorporated by reference in their entirety and made part of thisapplication.

Illustrative Embodiments

1. An introducer sheath for the insertion of a medical device into ablood vessel, the introducer sheath comprising:

-   -   an expandable sheath frame having a length, a first thickness, a        proximal end and a distal end;    -   the frame comprising a plurality of strands extending        longitudinally between the proximal end and the distal end, and        having an exterior surface and an interior surface that form an        interior lumen along the length of the frame;    -   the frame being configured to achieve an expanded state and a        contracted state, the expanded state forming an expanded        cross-section in the lumen for passing a medical device        therethrough; and    -   the frame having a smooth coating about the exterior surface and        protrusions extending into the lumen along the interior surface.

2. The introducer sheath of 1, further comprising a polymer layercovering an outer circumference of the frame and forming the smoothcoating.

3. The introducer sheath of any of 1 and 2, wherein the expandablesheath frame comprises an expansion mechanism configured to allow theframe to expand and contract.

4. The introducer sheath of 3, wherein the expansion mechanism comprisesthe plurality of strands configured with a bias to expand or contractfrom a resting position.

5. The introducer sheath of any of 3 and 4, wherein the expansionmechanism is configured to permit the strands to slide relative to eachother when the frame expands and contracts.

6. The introducer sheath of any of 1-5, wherein the plurality of strandscomprise first and second overlapping strands, with the second strandextending radially inward from the first strand.

7. The introducer sheath of 6, wherein the second strand overlaps withthe first strand and forms a plurality of peaks that project into thelumen.

8. The introducer sheath of any of 1-7, wherein the coating extendsabout the interior surface.

9. The introducer sheath of any of 1-8, wherein the coating covers theprotrusions along the interior surface.

10. The introducer sheath of 9, wherein the coating covering theprotrusions has a first thickness and the coating extending about theexterior surface has a second thickness.

11. The introducer sheath of 10, wherein the first thickness is lessthan the second thickness.

12. The introducer sheath of any of 6-11, wherein the first strand isbounded on an upper side by the smooth exterior surface coating.

13. The introducer sheath of any of 6-12, wherein the coating covers thesecond strand along a first longitudinal side of the second strand.

14. The introducer sheath of any of 6-13, wherein the coating covers anexterior-facing side of the first strand and an interior facing side ofthe second strand.

15. The introducer sheath of any of 1-14, wherein the frame comprises abraided mesh formed of a first plurality of strands.

16. The introducer sheath of 15, the first plurality of strands beingwrapped in a spiral direction along the length.

17. The introducer sheath of any of 15 and 16, wherein the framecomprises a second plurality of strands.

18. The introducer sheath of 17, wherein the second plurality of strandsare wrapped in a counter-clock-wise direction along the length.

19. The introducer sheath of any of 2-18, wherein a thickness of thepolymer layer is less than a thickness of the protrusions extending intothe lumen along the interior surface.

20. The introducer sheath of 19, wherein a thickness of the coating isless than the thickness of the polymer layer.

1. The introducer sheath of 19, wherein the thickness of the protrusionsis less than a thickness of a strand of the first plurality of strands.

22. The introducer sheath of 21, wherein the thickness of theprotrusions is less than about 75 or 100 μm.

23. The introducer sheath of any of 1-22, further comprising a sheathtip at the distal end of the expandable sheath frame, the sheath tiphaving a thickness, wherein the sheath tip thickness is greater than thethickness of the expandable sheath frame.

24. The introducer sheath of 23, wherein at least one of the frame,polymer layer and coating of the sheath tip is thicker than the frame,polymer layer and coating of the sheath.

25. The introducer sheath of any of 23 and 24, wherein the sheath tip ispolymer.

26. The introducer sheath of 25, wherein the polymer is co-molded withthe coating on the sheath frame.

27. The introducer sheath of any of 23-26, wherein the sheath tip ismade of a first material and the expandable sheath is made of a secondmaterial different than the first material.

28. The introducer sheath of 27, wherein the first material has adifferent stiffness than the second material.

29. The introducer sheath of any of 23-28, wherein the distal tip of thesheath is stiffer than the proximal end of the sheath.

30. A dilator assembly for the insertion of a medical device into ablood vessel, the dilator assembly comprising:

-   -   an inner dilator having a first length, a lumen between proximal        and distal ends of the inner dilator;    -   an outer dilator having a second length and a lumen between        proximal and distal ends of the outer dilator, wherein the outer        dilator is coaxial with the inner dilator and the first length        is greater than the second length;    -   the outer dilator and the inner dilator are spaced apart        radially by a circumferential gap having a gap thickness.

31. The dilator assembly of 30, wherein the inner dilator comprises:

-   -   a shaft extending through the lumen of the outer dilator; and    -   a distal tip forming a cavity about the distal end of the inner        dilator.

32. The dilator assembly of 31, wherein the cavity has an inner wall, aclosed end, and an open proximal end sized to receive the distal end ofthe outer dilator.

33. The dilator assembly of 32, wherein the inner wall has a diametergreater than the diameter of the inner dilator shaft.

34. The dilator assembly of 33, wherein the distal end of the outerdilator extends axially along the inner wall within the cavity to aposition between the closed end and the open proximal end, forming asheath tip receptacle.

35. The dilator assembly of any of 30-34, wherein the outer dilatorcomprises:

-   -   a proximal portion with a first diameter,    -   a distal portion with a second diameter, wherein the second        diameter is smaller than the first diameter, and    -   a conical transition portion between the proximal portion and        the distal portion.

36. The dilator assembly of 35, wherein the second diameter of the outerdilator is substantially equal to an outer diameter of a tip of theinner dilator

37. A sheath assembly comprising an introducer sheath according to anyof 1-29, and a dilator assembly according to any of 30-36.

38. The sheath assembly of 37, wherein the inner dilator and outerdilator are configured to be inserted into the first lumen of theexpandable sheath frame to adjust a diameter of the expandable sheathframe.

39. The sheath assembly of 38, wherein the head is bonded to the distalend of the dilator.

40. The sheath assembly of 39, wherein the second thickness is greaterthan the thickness of the sheath frame such that the sheath frame fitswithin the circumferential gap, the sheath tip fits within the sheathtip receptacle, and the second thickness is smaller than the thicknessof the sheath tip such that the sheath tip is retained within thedilator tip.

41. A method of manufacturing an expandable introducer sheath, themethod comprising:

-   -   priming a sheath frame using a priming solution, wherein the        sheath frame is primed for adhesion to a polymer layer;    -   assembling the polymer layer over the sheath frame;    -   bonding the polymer layer and the sheath frame by exposing the        polymer layer and the sheath frame to air for a duration of        time, wherein the air is heated to a first temperature; and    -   coating an inner surface of the polymer layer and the sheath        frame with a lubricious material.

42. The method of 41, further comprising coating an outer surface of thepolymer layer and the sheath frame with the lubricious material.

43. An introducer sheath for the insertion of a medical device into ablood vessel, the introducer sheath comprising:

-   -   an expandable sheath body having a first length, a longitudinal        axis, and proximal and distal ends, the expandable sheath body        comprising:        -   a braid forming a first lumen, the first lumen extending            between the proximal and distal ends of the expandable            sheath body, the first lumen having a first diameter in a            first elongated state and a second diameter in a second            relaxed state, wherein the second diameter in the second            relaxed state is sized to accommodate the medical device,            the braid formed of at least one strand of a first material            extending from the proximal end of the expandable sheath            body at an acute angle relative to the longitudinal axis of            the expandable sheath body; and        -   a polymer encapsulating at least a distal portion of the            braid, wherein the polymer is configured to expand or            collapse along with the braid, the acute angle and the first            material selected to allow the medical device to pass            through the expandable sheath body in the second relaxed            state.

44. The introducer sheath of 43, wherein the braid comprises a firstplurality of strands wrapped in a clock-wise spiral direction along thefirst length and a second plurality of strands wrapped in acounter-clock-wise spiral direction along the first length.

45. The introducer sheath of 44, wherein the first plurality of strandsand the second plurality of strands are radiopaque.

46. The introducer sheath of any of 44 and 45, wherein an angle betweenthe first plurality of strands and the second plurality of strands is atabout 35 degrees, 45 degrees, or 55 degrees.

47. The introducer sheath of any of 44-46, wherein the braid comprises abraid pattern defined by the first plurality of strands and the secondplurality of strands.

48. The introducer sheath of 47, wherein the braid pattern definesrhombi, each rhombi comprising a first corner and a second corneradjacent the first corner.

49. The introducer sheath of 48, wherein at least one strand of thefirst plurality of strands goes over at least one strand of the secondplurality of strands at the first corner and the at least one strand ofthe first plurality of strands goes over the at least one strand of thesecond plurality of strands at the second corner.

50. The introducer sheath of 48, wherein at least one strand of thefirst plurality of strands goes over at least one strand of the secondplurality of strands at the first corner and the at least one strand ofthe first plurality of strands goes under the at least one strand of thesecond plurality of strands at the second corner.

51. The introducer sheath of any of 43-50, wherein the first material ofthe at least one strand comprises a metal.

52. The introducer sheath of any of 43-51, wherein the first material ofthe at least one strand comprises at least one of Nitinol round wire,Nitinol flat wire, Stainless steel round wire, stainless steel flatwire, liquid crystal polymer, polyimide, and polyether ether ketone(PEEK).

53. The introducer sheath of any of 43-52, wherein the polymer comprisesone of silicone and thermoplastic polyurethane.

54. The introducer sheath of any of 43-53, further comprising a hubhaving a second length and a second lumen extending between proximal anddistal ends of the hub, wherein the distal end of the hub is attached tothe proximal end of the expandable sheath body and the second lumen ofthe hub is in communication with the first lumen of the sheath.

55. The introducer sheath of 54, wherein the hub further comprises ahemostasis valve within the second lumen, wherein the hemostasis valveis configured for insertion of a component.

56. The introducer sheath of any of 54 and 55, wherein the hub furthercomprises a side-arm that allows for flushing and aspiration of theintroducer sheath.

57. The introducer sheath of any of 43-56, wherein the polymerencapsulates the entire braid.

58. The introducer sheath of any of 43-57, further comprising ahydrophilic material coating at least a portion of an inner surface ofthe polymer.

59. The introducer sheath of 58, wherein the hydrophilic material coatsat least a portion of an outer surface of the polymer.

60. The introducer sheath of any of 43-59, wherein an inner surface ofthe polymer comprises a smooth surface and an outer surface of thepolymer comprises at least one trough.

61. The introducer sheath of any of 43-60, wherein an inner surface ofthe polymer comprises at least one trough and an outer surface of thepolymer comprises a smooth surface.

62. The introducer sheath of any of 43-61, wherein the proximal end ofthe expandable sheath body lies outside of a body of a patient.

63. The introducer sheath of any of 43-62, wherein the introducer sheathis configured for the insertion of a blood pump into a blood vessel.

64. The introducer sheath of any of 43-63, further comprising at thedistal end of the expandable sheath body a distal portion of the firstlumen shaped such that an inner diameter of the distal portion isdifferent from that of the first lumen.

65. The introducer sheath of any of 43-64, further comprising at thedistal end of the expandable sheath body a distal portion of the firstlumen, the distal portion shaped to reversibly lock with a distal end ofa dilator.

66. An introducer sheath for the insertion of a medical device into ablood vessel, the introducer sheath comprising:

-   -   an expandable sheath body having a first length, a longitudinal        axis, and proximal and distal ends, the expandable sheath body        comprising:        -   a braid forming a first lumen, the first lumen extending            between the proximal and distal ends of the expandable            sheath body, the first lumen having a first diameter in a            first elongated state, a second diameter in a second relaxed            state, and a third diameter in a third expanded state,            wherein the first diameter in the first elongated state is            sized to insert the expandable sheath body in the blood            vessel, and wherein the third diameter in the third expanded            state is sized to accommodate the medical device, the braid            formed of at least one strand of a first material extending            from the proximal end of the expandable sheath body at an            acute angle relative to the longitudinal axis of the            expandable sheath body; and        -   a polymer encapsulating at least a distal portion of the            braid, wherein the polymer is configured to expand or            collapse along with the braid, the acute angle and the first            material selected to allow the medical device to pass            through the expandable sheath body in the third expanded            state.

67. An introducer sheath for the insertion of a medical device into ablood vessel, the introducer sheath comprising:

-   -   an expandable sheath body having a first length, a longitudinal        axis, and proximal and distal ends, the expandable sheath body        comprising:        -   a braid forming a first lumen, the first lumen extending            between the proximal and distal ends of the expandable            sheath body, the first lumen having a first diameter in a            first relaxed state and a second diameter in a second            expanded state, wherein the second diameter in the second            expanded state is sized to accommodate the medical device,            the braid formed of at least one strand of a first material            extending from the proximal end of the expandable sheath            body at an acute angle relative to the longitudinal axis of            the expandable sheath body; and        -   a polymer encapsulating at least a distal portion of the            braid, wherein the polymer can expand or collapse along with            the braid, the acute angle and the first material selected            to allow the medical device to pass through the expandable            sheath body in the second expanded state.

68. A sheath assembly for the insertion of a medical device into a bloodvessel, the sheath assembly comprising:

-   -   an introducer sheath comprising:        -   an expandable sheath body having a first length, a            longitudinal axis, and proximal and distal ends, the            expandable sheath body comprising:        -   a first lumen extending between the proximal and distal ends            of the expandable sheath body, the first lumen having a            first diameter in a first elongated state and a second            diameter in a second relaxed state, wherein the second            diameter in the second relaxed state is sized to accommodate            the medical device;        -   a braid forming the first lumen, the braid formed of at            least one strand of a first material extending from the            proximal end of the expandable sheath body at an acute angle            relative to the longitudinal axis of the expandable sheath            body; and        -   a polymer encapsulating at least a distal portion of the            braid, wherein the polymer can expand or collapse along with            the braid, the acute angle and the first material selected            to allow the medical device to pass through the expandable            sheath body without the expandable sheath body buckling; and    -   a dilator assembly comprising:        -   an inner dilator having a second length and a second lumen            between proximal and distal ends of the inner dilator;        -   an outer dilator having a third length and a third lumen            between proximal and distal ends of the outer dilator,            wherein the outer dilator is axially aligned with the inner            dilator and the second length is greater than the third            length,        -   wherein the inner dilator and outer dilator are configured            to be inserted into the first lumen of the expandable sheath            body to adjust a diameter of the expandable sheath; and        -   a hub attachment having a third length and a third lumen            between proximal and distal ends of the hub attachment,            wherein the hub attachment is axially aligned with the outer            dilator and inner dilator and the outer dilator and inner            dilator lie within the third lumen, wherein the distal end            of the hub attachment is attached to a proximal end of the            introducer sheath.

69. A sheath assembly for the insertion of a medical device into a bloodvessel, the sheath assembly comprising:

-   -   an introducer sheath comprising:        -   an expandable sheath body having a first length, a            longitudinal axis, and proximal and distal ends, the            expandable sheath body comprising:        -   a first lumen extending between the proximal and distal ends            of the expandable sheath body, the first lumen having a            first diameter in a first elongated state and a second            diameter in a second relaxed state, wherein the second            diameter in the second relaxed state is sized to accommodate            the medical device;        -   a braid forming the first lumen, the braid formed of at            least one strand of a first material extending from the            proximal end of the expandable sheath body at an acute angle            relative to the longitudinal axis of the expandable sheath            body; and        -   a polymer encapsulating at least a distal portion of the            braid, wherein the polymer can expand or collapse along with            the braid, the acute angle and the first material selected            to allow the medical device to pass through the expandable            sheath body without the expandable sheath body buckling; and    -   a hemostasis stylet assembly comprising:        -   a locking hub having distal and proximal ends, the distal            end configured to attach to a proximal end of the introducer            sheath;        -   a hemostasis stylet having distal and proximal ends, the            hemostasis stylet comprising:            -   a hemostasis stylet body having distal and proximal                ends, wherein the distal end of the hemostasis stylet                body is configured to be inserted into an expandable                sheath of the introducer assembly in order to control                hemostasis between the expandable sheath and an opening                of a blood vessel; and        -   a first sterile layer having a first length and a first            lumen between distal and proximal ends of the first sterile            layer, wherein the proximal end of the first sterile layer            is attached to the distal end of the locking hub of the            hemostasis stylet; and        -   a second sterile layer having a second length and a second            lumen between distal and proximal ends of the second sterile            layer, wherein the distal end of the second sterile layer is            attached to the proximal end of the locking hub of the            hemostasis stylet.

70. The introducer sheath of 69, wherein the sheath assembly furthercomprises:

-   -   a hub having a lumen between distal and proximal ends of the        hub, wherein the hemostasis stylet body is attached to the        proximal end of the hemostasis stylet hub.

71. A sheath assembly for the insertion of a medical device into a bloodvessel, the sheath assembly comprising:

-   -   an introducer sheath comprising:        -   an expandable sheath body having a first length, a            longitudinal axis, and proximal and distal ends, the            expandable sheath body comprising:        -   a first lumen extending between the proximal and distal ends            of the expandable sheath body, the first lumen having a            first diameter in a first elongated state and a second            diameter in a second relaxed state, wherein the second            diameter in the second relaxed state is sized to accommodate            the medical device;        -   a braid forming the first lumen, the braid formed of at            least one strand of a first material extending from the            proximal end of the expandable sheath body at an acute angle            relative to the longitudinal axis of the expandable sheath            body; and        -   a polymer encapsulating at least a distal portion of the            braid, wherein the polymer can expand or collapse along with            the braid, the acute angle and the first material selected            to allow the medical device to pass through the expandable            sheath body without the expandable sheath body buckling; and    -   a dilator assembly comprising:        -   an inner dilator having a second length and a second lumen            between proximal and distal ends of the inner dilator;        -   an outer dilator having a third length and a third lumen            between proximal and distal ends of the outer dilator,            wherein the outer dilator is axially aligned with the inner            dilator and the second length is greater than the third            length,        -   wherein the inner dilator and outer dilator are configured            to be inserted into the first lumen of the expandable sheath            body to adjust a diameter of the expandable sheath; and        -   a hub attachment having a third length and a third lumen            between proximal and distal ends of the hub attachment,            wherein the hub attachment is axially aligned with the outer            dilator and the outer dilator lies within the third lumen,            wherein the distal end of the hub attachment is attached to            a proximal end of the introducer sheath; and    -   a hemostasis stylet assembly comprising:        -   a locking hub having distal and proximal ends, the distal            end configured to attach to a proximal end of the introducer            sheath;        -   a hemostasis stylet having distal and proximal ends, the            hemostasis stylet comprising:            -   a hemostasis stylet hub having a lumen between distal                and proximal ends of the hemostasis stylet hub, wherein                a first sterile layer and a hemostasis stylet body are                attached to the distal end of the hemostasis stylet hub                and a second sterile layer is attached to the proximal                end of the hemostasis stylet hub; and            -   the hemostasis stylet body having distal and proximal                ends, wherein the distal end of the hemostasis stylet                body is configured to be inserted into an expandable                sheath of the introducer assembly in order to control                hemostasis between the expandable sheath and an opening                of a blood vessel; and        -   the first sterile layer having a first length and a first            lumen between distal and proximal ends of the first sterile            layer, wherein the distal end of the first sterile layer is            attached to the locking hub; and        -   a second sterile layer having a second length and a second            lumen between distal and proximal ends of the second sterile            layer.

72. A method of inserting a pump into a blood vessel, the methodcomprising:

-   -   attaching an introducer assembly to a dilator assembly, the        introducer assembly comprising an expandable sheath having a        first diameter and a first length;    -   moving the dilator assembly with respect to the introducer        assembly in the proximal direction, wherein the expandable        sheath of the introducer assembly transitions to a second        diameter and a second length, wherein the second diameter is        smaller than the first diameter and the second length is greater        than the first length;    -   inserting the introducer assembly and the dilator assembly into        a desired location in a blood vessel, wherein an opening of the        blood vessel expands to accommodate the second diameter of the        expandable sheath;    -   moving the dilator assembly with respect to the introducer        assembly in the distal direction, wherein the expandable sheath        of the introducer assembly expands to a third diameter and a        third length, wherein the third diameter is greater than the        second diameter and the third length is smaller than the second        length, wherein the opening of the blood vessel expands to        accommodate the third diameter of the expandable sheath;    -   detaching the dilator assembly from the introducer assembly and        removing the dilator assembly from the desired location in the        blood vessel;    -   inserting a pump through the introducer assembly, wherein the        expandable sheath expands to a fourth diameter to accommodate        the pump as the pump traverses within the introducer assembly,        wherein the fourth diameter is greater than the third diameter        and the opening of the blood vessel expands to accommodate the        fourth diameter of the expandable sheath; and        -   inserting a hemostasis stylet through the introducer            assembly, wherein the expandable sheath expands to the            fourth diameter sized to accommodate the hemostasis stylet            as the hemostasis stylet traverses within the introducer            assembly, wherein the fifth diameter is selected to            facilitate hemostasis between the opening of the blood            vessel and the expandable sheath.

73. A blood pump system, the blood pump system comprising:

-   -   a blood pump coupled to a catheter having proximal and distal        ends;    -   an introducer sheath, wherein the introducer sheath is sized to        accommodate the blood pump during insertion into the blood        vessel; and    -   a repositioning sheath assembly comprising:        -   a repositioning sheath;        -   a first sterile sleeve having a first length and a first            lumen between distal and proximal ends of the first sterile            sleeve, wherein the distal end of the first sterile sleeve            is attached to the proximal end of the repositioning sheath;        -   the repositioning sheath having distal and proximal ends,            wherein the distal end of the repositioning sheath is            configured to be inserted into the introducer sheath in            order to control hemostasis between the introducer sheath            and an opening of the blood vessel;        -   a second sterile sleeve having a second length and a second            lumen between distal and proximal ends of the second sterile            sleeve, wherein the proximal end of the second sterile            sleeve is attached to the proximal end of the repositioning            sheath, and the distal end of the second sterile sleeve is            attached to a proximal end of the introducer sheath.

74. The blood pump system of 73 further comprising the introducer sheathof any of 1-67.

75. The blood pump system of any of 73 and 74, wherein the first sterilesleeve and the second sterile sleeve are flexible.

76. The blood pump system of any of 73-75, wherein the first sterilesleeve comprises a first plurality of flexible layers and the secondsterile sleeve comprises a second plurality of flexible layers.

77. The blood pump system of 73-76, wherein the first and secondplurality of flexible layers comprises a flexible material.

78. The blood pump system of any of 73-77, wherein the catheter extendsthrough: the first sterile sleeve, the repositioning sheath, the secondsterile sleeve, and the introducer sheath.

79. The blood pump system of 78, wherein the catheter extends slideablythrough the first sterile sleeve and the second sterile sleeve.

80. The blood pump system of any of 78 and 79, wherein the repositioningsheath is configured to move relative to the catheter.

81. The blood pump system of 80, wherein at least one of the first andsecond sterile sleeves is configured to be reduced in length when therepositioning sheath is configured to move relative to the catheter.

82. The blood pump system of any of 73-81, wherein the introducer sheathcomprises:

-   -   an expandable sheath frame having a length, a first thickness, a        proximal end and a distal end;    -   the frame comprising a plurality of strands extending        longitudinally between the proximal end and the distal end, and        having an exterior surface and an interior surface that form an        interior lumen along the length of the frame;    -   the frame being configured to achieve an expanded state and a        contracted state, the expanded state forming an expanded        cross-section in the lumen for passing a medical device        therethrough; and    -   the frame having a smooth coating about the exterior surface and        protrusions extending into the lumen along the interior surface.

1-20. (canceled)
 21. An introducer sheath for the insertion of a medicaldevice into a blood vessel, the introducer sheath comprising: anexpandable sheath frame having a length, a first thickness, a proximalend and a distal end; the frame comprising a plurality of strandsextending longitudinally between the proximal end and the distal end,and having an exterior surface and an interior surface that form aninterior lumen along the length of the frame; the frame being configuredto achieve an expanded state and a contracted state, the expanded stateforming an expanded cross-section in the lumen for passing a medicaldevice therethrough; and the frame having a smooth coating about theexterior surface and protrusions extending into the lumen along theinterior surface.
 22. The introducer sheath of claim 21, furthercomprising a polymer layer covering an outer circumference of the frameand forming the smooth coating.
 23. The introducer sheath of claim 21,wherein the expandable sheath frame comprises an expansion mechanismconfigured to allow the frame to expand and contract.
 24. The introducersheath of claim 23, wherein the expansion mechanism comprises theplurality of strands configured with a bias to expand or contract from aresting position.
 25. The introducer sheath of claim 24, wherein theexpansion mechanism is configured to permit the strands to sliderelative to each other when the frame expands and contracts.
 26. Theintroducer sheath of claim 21, wherein the plurality of strands comprisefirst and second overlapping strands, with the second strand extendingradially inward from the first strand.
 27. The introducer sheath ofclaim 26, wherein the second strand overlaps with the first strand andforms a plurality of peaks that project into the lumen.
 28. Theintroducer sheath of claim 21, wherein the coating extends about theinterior surface.
 29. The introducer sheath of claim 21, wherein thecoating covers the protrusions along the interior surface.
 30. Theintroducer sheath of claim 29, wherein the coating covering theprotrusions has a first thickness and the coating extending about theexterior surface has a second thickness.
 31. The introducer sheath ofclaim 30, wherein the first thickness is less than the second thickness.32. The introducer sheath of claim 21, wherein the frame comprises abraided mesh formed of a first plurality of strands.
 33. The introducersheath of claim 32, the first plurality of strands being wrapped in aspiral direction along the length.
 34. The introducer sheath of claim33, wherein the frame comprises a second plurality of strands.
 35. Theintroducer sheath of claim 22, wherein a thickness of the polymer layeris less than a thickness of the protrusions extending into the lumenalong the interior surface.
 36. The introducer sheath of claim 35,wherein a thickness of the coating is less than the thickness of thepolymer layer.
 37. The introducer sheath of claim 35, wherein thethickness of the protrusions is less than a thickness of a strand of theplurality of strands.
 38. The introducer sheath of any of claim 21,further comprising a sheath tip at the distal end of the expandablesheath frame, the sheath tip having a thickness, wherein the sheath tipthickness is greater than the thickness of the expandable sheath frame.39. The introducer sheath of claim 38, wherein the sheath tip is made ofa first material and the expandable sheath is made of a second materialdifferent than the first material.
 40. The introducer sheath of claim38, wherein the distal tip of the sheath is stiffer than the proximalend of the sheath.